Maybe missing tree is what has broken my save.
Had a situation long time ago where something happened to the White Birch tree workshop asset.
I had a whole bunch of them in my save.

One day I got an error message of some sort (dont ask me to remember exactly what it said - it may of been "found duplicate" but don't quote me on it) and from then on the White Birch trees in my save appeared weird looking (different).

(The duplicate message was because I had edited the asset only because I wanted a version with a preview photo so that I could find it easier in the game.) But I don't think this was the cause of making the trees appear weird, because I had made the copy a long time ago.

I didn't bother to delete them and replace them for a long time, until recently .... but it was before the latest CS update.

A strange thing happened when I went to delete them .... it would take multiple clicks just to delete one .... then when I saved and restarted the game, the trees would be back. I tried it a few times, each time the same thing would happen after the save, but at least now it was taking less and less times to click to delete one. This continued until it took only one click to delete each tree (back to normal).

Meanwhile I had unsubscribed both the workshop version and my private version of the White Birch tree asset. And now when I would restart the save the trees were replaced with one of the other workshop tree assets I had subscribed to. I unsubscribed from the tree asset that now appeared, and long story short I had to unsubscribe from all the workshop tree assets I had in order for no trees to reappear.

I don't think this fixed whatever problem there was, because if I tried subscribing to any workshop tree asset, even one I hadn't had before, the new trees would appear in place of where the original White Birch trees had been.

Anyway .... a little bit of time passed and my save would still load normally (albeit with 4 assets with LOD too many vertices error), until the day the latest CS update was applied. After that my save was broken and still is to this day.

Any ideas? .... lol

Try SOS? (Save Our Saves mod) I never used it but seems like it was designed for such a situation

@chaosmercenary I agree... the S.O.S mod is made for this. It checks all prop/tree/building/vehicle instances and deletes the ones that have no asset loaded.

@I AM BORG I also have the experience that the CS update two weeks ago made the game more sensitive to missing custom assets.

As mentioned above, S.O.S is worth trying. If successful, it will clean up your city a bit. If you suspect some asset is behind the problem, unsub it and run S.O.S again.

Tried S.O.S. .... didn't fix it.

Thanks for the explanation! I was going crazy re-subscribing to stuff. I guess it doesn't really make that much of a difference for me cause it's just minor visual stuff, but is there any way to contact the person who made the props? It's pretty much only Kowamurka's props, but also 萬朶櫻(wanduoying)'s abandoned train stations.

@картошка The building is a workshop asset, so its Steam page is the best bet.

BUG is too more....can see this？ I'm not familiar with this
=====================
新都

Report created at time 1:31.
To stop saving these files, disable the option "Save assets report" in Loading Screen Mod.
You can safely delete this file. No-one reads it except you.
Assets that failed to load

418205510.Hiraya_00 1x1_Data
481423357.Ocean Liner (stationary)_Data
Duplicate assets

No duplicates were found (in Cities Skylines, each 'PackageName.AssetName' must be unique).
Assets that were not found

Note: the following assets are used in your city but could not be found. You should get the assets if possible. These cases can break savegames.
579726271.fishing boat_Data

Note: the following missing assets are used in buildings and parks. These cases do not break savegames.
425666746.cherryblossom(벚나무)_Data
Required in: 442819735.Japanese Spirit House Garden_Data
425666746.벚나무(cherryblossom)_Data
Required in: 683714366.Japanese Shrine_Data
441482417.Green Pine Oak Tree_Data
Required in: 442819735.Japanese Spirit House Garden_Data
You have 441482417 but it does not contain Green Pine Oak Tree_Data. Name probably changed by the author
441482464.Yellow Pine Oak Tree_Data
Required in: 442819735.Japanese Spirit House Garden_Data
You have 441482464 but it does not contain Yellow Pine Oak Tree_Data. Name probably changed by the author
441482500.Orange Pine Oak Tree_Data
Required in: 442819735.Japanese Spirit House Garden_Data
You have 441482500 but it does not contain Orange Pine Oak Tree_Data. Name probably changed by the author
487141618.MAN_Data
Required in: 660491645.Baugrube_Basis_Data
You have 487141618 but it does not contain MAN_Data. Name probably changed by the author
614749507.Front Loader Straight_Data
Required in: 660491645.Baugrube_Erweiterung01_Data
You have 614749507 but it does not contain Front Loader Straight_Data. Name probably changed by the author
door.shirakawa_door_Data
Required in: 678813085.shirakawa_go_Data
Workshop asset requires private content, seems like asset bug
Dream Dongas 02.Dream Dongas 02_Data
Required in: 480425628.Dream Tower Under Construction_Data
Workshop asset requires private content, seems like asset bug
Dream Dongas Double.Dream Dongas Double_Data
Required in: 480425628.Dream Tower Under Construction_Data
Workshop asset requires private content, seems like asset bug
Dream Guard Shack 02 [PROP].Dream Guard Shack 02 [PROP]_Data
Required in: 480425628.Dream Tower Under Construction_Data
Workshop asset requires private content, seems like asset bug
Fence_Zaun.Fence_Zaun_Data
Required in: 426391662.Saladfield_Data
Workshop asset requires private content, seems like asset bug
J-Wall Style-1 Corner.J-Wall Style-1 Corner_Data
Required in: 489843405.J-Temple-2-Style-1_Data
Workshop asset requires private content, seems like asset bug
J-Wall Style-1 Straight.J-Wall Style-1 Straight_Data
Required in: 489843405.J-Temple-2-Style-1_Data
Workshop asset requires private content, seems like asset bug
Platform_Data
Required in: 411252848.RX-78-2 Gundam Statue_Data
Probably a Workshop prop or tree but no link is available
salat_line.salat_line_Data
Required in: 426391662.Saladfield_Data
Workshop asset requires private content, seems like asset bug
Soviet antenna.Soviet antenna_Data
Required in: 409323913.Хрущёвка серии 1-464_Data
531899368.L1 1-464 Soviet apartment_Data
532414816.L2 1-464 Soviet apartment_Data
532415411.L3 1-464 Soviet apartment_Data
Workshop asset requires private content, seems like asset bug
Torii Gate v2.Torii Gate v2_Data
Required in: 489843405.J-Temple-2-Style-1_Data
Workshop asset requires private content, seems like asset bug
Строительный забор.Строительный забор_Data
Required in: 540307672.Хрущевка10_Data
Workshop asset requires private content, seems like asset bug
Турник.Турник_Data
Required in: 539531527.Хрущевка 5 этажей_Data
539572090.Хрущевка 5 этажей_Data
Workshop asset requires private content, seems like asset bug
プロパンガスボンベ.プロパンガスボンベ_Data
Required in: 499717292.海の家れもん_Data
500209986.タヌキ商店_Data
502042316.日本民家4x3 L4_Data
502045547.御茶處 飛雲庵_Data
507190803.向新、泉佐野店_Data
537723963.きさらぎ綫かたす驛_Data
686813905.向新、和歌山北店_Data
Workshop asset requires private content, seems like asset bug
井戸01.井戸01_Data
Required in: 537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
商業看板_大.商業看板_大_Data
Required in: 551398200.向新、貝塚店_Data
Workshop asset requires private content, seems like asset bug
幟001.幟001_Data
Required in: 502045547.御茶處 飛雲庵_Data
Workshop asset requires private content, seems like asset bug
幟002.幟002_Data
Required in: 507190803.向新、泉佐野店_Data
537719418.向新、岸和田店_Data
686813238.向新、熊取店_Data
686813441.向新、岩出店_Data
686813592.向新、葛の葉店_Data
Workshop asset requires private content, seems like asset bug
廢驛_かたす驛驛名表示G-T.かたす驛驛名表示G-T_Data
Required in: 537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_かたす驛驛名表示T-G.かたす驛驛名表示T-G_Data
Required in: 537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_きさらぎ驛看板.きさらぎ驛看板_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_きさらぎ驛驛名表示.きさらぎ驛驛名表示_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_ベンチ.廢驛のベンチ_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
500209986.タヌキ商店_Data
500232172.泉州航空神社_Data
502045547.御茶處 飛雲庵_Data
537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_便所01.廢驛の便所01_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_廢棄物001.廢驛_廢棄物001_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_待合室02.廢驛の待合室02_Data
Required in: 502045547.御茶處 飛雲庵_Data
537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
廢驛_電燈.廢驛の電燈_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
新規アセット.新規アセット_Data
Required in: 500232172.泉州航空神社_Data
Workshop asset requires private content, seems like asset bug
泉州航空神社_ヘリコプター.泉州航空神社ヘリコプター_Data
Required in: 500232172.泉州航空神社_Data
502045547.御茶處 飛雲庵_Data
Workshop asset requires private content, seems like asset bug
泉州航空神社_手水.泉州航空神社手水_Data
Required in: 500232172.泉州航空神社_Data
Workshop asset requires private content, seems like asset bug
泉州航空神社_看板.泉州航空神社看板_Data
Required in: 502045547.御茶處 飛雲庵_Data
507190803.向新、泉佐野店_Data
686813238.向新、熊取店_Data
686813905.向新、和歌山北店_Data
Workshop asset requires private content, seems like asset bug
海の家れもん_侵略看板01.海の家れもん侵略看板01_Data
Required in: 499717292.海の家れもん_Data
Workshop asset requires private content, seems like asset bug
海の家れもん_侵略看板02.海の家れもん侵略看板02_Data
Required in: 499717292.海の家れもん_Data
500209986.タヌキ商店_Data
502045547.御茶處 飛雲庵_Data
507190803.向新、泉佐野店_Data
537719418.向新、岸和田店_Data
686813592.向新、葛の葉店_Data
686813905.向新、和歌山北店_Data
Workshop asset requires private content, seems like asset bug
燃2弾4鋼11.燃2弾4鋼11_Data
Required in: 498530521.きさらぎ綫きさらぎ驛_Data
500232172.泉州航空神社_Data
Workshop asset requires private content, seems like asset bug
石塀.石塀_Data
Required in: 502042316.日本民家4x3 L4_Data
537719418.向新、岸和田店_Data
537723963.きさらぎ綫かたす驛_Data
Workshop asset requires private content, seems like asset bug
竹柵.竹柵_Data
Required in: 502045547.御茶處 飛雲庵_Data
686813726.向新、富田林店_Data
Workshop asset requires private content, seems like asset bug
電燈.笠かぶりの電燈_Data
Required in: 500232172.泉州航空神社_Data
Workshop asset requires private content, seems like asset bug
鳥居_朱_プロペラprop.泉州航空神社鳥居_Data
Required in: 500232172.泉州航空神社_Data
Workshop asset requires private content, seems like asset bug
鳥居_石_一本足右prop.片足鳥居(右半分)_Data
Required in: 490548254.片足鳥居_Data
Workshop asset requires private content, seems like asset bug
鳥居_石_一本足左prop.片足鳥居(左半分)_Data
Required in: 490548254.片足鳥居_Data
498530521.きさらぎ綫きさらぎ驛_Data
Workshop asset requires private content, seems like asset bug
The following custom assets are used in this city

@[CN/JPN]星野さん Is there a problem with that report? By the way, it is better to paste large files to Gist or pastebin, and submit the link.

I have one item that's got a bug, probably due to the name change by the looks of it "Utility_Poles_Advertisement.Utility Poles Advertisement_Data" (but is no longer the name of it), As this item/data is Required for

1115787102.Utility Poles(32m x 4)_Data,
1115787102.Utility Poles(32m)_Data,
1115787102.Utility Poles(24m)_Data,
1115787102.Utility Poles(32m) with Trans_Data,

These items links are located under the creator's profile at https://steamcommunity.com/profiles/76561198063450045/myworkshopfiles/?appid=255710

It states that the Workshop asset requires private content, seems like an "Asset bug"

However, they still work by the looks of it. So it's something you may wish to look at whenever you have the time...

Cheers