Valve need to fix majors issues such as:

1-Solve cheats / bots related problems. Sue nasty individuals hosting cheats and bots on their websites. Forgot your own Steam rules, Valve ?
https://store.steampowered.com/online_conduct/?l=english&snr=2_groupannouncements_detail_

2-Use permabans when needed. Most cheaters have total impunity these days. Some of them are well known in the community and ruined TF2 for a decade.

3-Update your VAC system because this is an outdated piece of crap by today's standards.

4-Stop neglecting TF2.

- - -

Now let's talk about few things:

Competitive Mode:

Remove it completely. Noboby plays it.
The unofficial "comp scene" have his own set of rules/weapons restrictions and leagues. Everyone knows "comp players" don't use your official version of competitive TF2.
This is just pointless to keep that "dead on arrival" competitive gamemode in the main menu.

TF2 was never designed to be a competitive game at his core and it shows.
It just doesn't work.

Not to mention it's nearly impossible to balance every weapons for both Competitive Mode and Casual Mode.

And considering unofficial comp scene is a very small part of the TF2 Community, the game shouldn't be balanced towards this vision of the game. We need random bullet spread "On", random crits "On", and kept the fun aspect of some weapons, this is a part of TF2 DNA.

- - -

Casual Mode:

The name "Casual Mode" is so misleading. Change it.
TF2 is the original name since 2007, and it is played by any type of players: from veterans players to regular players to casual players.

1-Better Balance System
The current one have so many flaws. Fix them.

2-Class Restrictions:
Force 2 slots maximum per class, it should be beneficial on a 24 slots server (meaning every team have at least 1 merc of each type). It will helps to NOT have 3 Spy, 3 Sniper or 3 Engineer (or more) per team which leads to unbalanced / boring rounds.

3-Temporary Bans:
Add a small temporary ban for the players who are leaving the game in the middle or before the end of the round.
Most rounds are ruined when few people leaves the server to join another one. They usually whenever they want, because they don't want to lose or don't care to ruin the round for others players. This is one of the main reasons why the matchmaking struggles to find new players to replace them quickly.

This small temporary ban will NOT affect players that are closing the game to do others things, because they'll leave it for a good reason and not requeue instantly for another server.

So the people who leaves the game before the end should receive this small temporary ban (like 5 min) and if they continue to leave another server the ban should increase to 10 min (and so on). Of course this system WILL ONLY work if you get rid of human cheaters and bots.

4-Weapons Stats Changes:
A lot of buffs and nerfs are needed.
-Talk with the community about that. Share and explain any changes into the TF2 Blog (like it was the case few years ago, it was great).


5-Additionnal ideas:
-Adding good community fixes that are in the TF2 Workshop since years.
-Adding new Tiers / Levels for the badge ? I personnally reach the maximum Casual Rank in March 2019. So if by any chance more ranks could be added, let's hope the XP points accumulated after reaching the max rank will not be wasted.

- - -

Cosmetics, Maps and Content:
1-Adding 1 extra cosmetics slot ?
Actually people want to equip all (or more of their items).
-One headgear, one facial misc, one upper body misc, and one lower body misc would make so much sense to fully equip your merc from head to toes.

2-Bringing back good and harsh quality control for the TF2 Workshop submissions ?
So many questionnable cosmetics have been added officially into the game and started to ruin the iconic TF2 artstyle since few years. Take notes:

https://youtu.be/8RAF-55O2-k

3-Stop adding truckload of unusual effects:
Most of them tends to ruin the TF2 artstyle and bloat this game even more.
Fun Fact: Nowadays you looks special when you don't wear unusuals...

4-Stop addind unfinished maps.
I mean pl_wutville was the worst map ever added officially in TF2.
Seriously what the heck...

5-Quality > Quantity
In 2023, 14 maps for Summer Update and 12 maps for Scream Fortress. 10 maps for Smissmas. 36 maps in 1 year. This game receive more maps this year alone, compared to the 5 previous years combined or something like that. Not to mention, half of them are bad/passable or broken on launch.

How about 2-3 very good maps per event maximum, it should be better and more than enough.

- - -

Scream Fortress:

And even if you play with 5 friends, it takes longer each year since more maps are added. I would rather suggest to remove contracts entirely at this point in time. And no rewards for completing every bonus ? What a joke. At least gave something for the players who completed them since 2018 (could be a specific medal or cosmetic). This is harsh...

- - -

Now:
TF2 is slowly dying since 2016 and TF2 players are fed up by all this bullsh.it.

1-The massive amount of cheaters and bots make this game unplayable.
Usually and in my experience 7/9 out of 10 games are ruined by bots and cheaters since 2016.

2-The lack of meaningful updates since 2017 / 2018 (Jungle Inferno and Blue Moon Update were the last majors updates).

3-Did you even remember what you said in response to the #SaveTF2 movement ?
https://twitter.com/TeamFortress/status/1529970640224018433
We're now 2 years later and none of the issues have been addressed...

This is an ABSOLUTE SHAME to see this masterpiece of a game on a such AWFUL state.

Last but not least, seeing TF2 dying because of cheats and lack of attention BUT still being monetised while most of the content is made since years by the TF2 community is infuriating.

And seeing Valve that take the biggest portion of the revenues while doing nothing but ruining his own game is insane, especially when your loyal playerbase asked you to fix this game since ~2016. From best developpers to worst. Fu.cking sad.