Ok, hear me out, last game i had a huge problem with lag spikes especially at the 1st of every month for the last couple of years before i temporarly fixed it, i tried multiple things but then found the reason.

https://steamcommunity.com/sharedfiles/filedetails/?id=2448802615

my colony with 222 pops, never stopped spawning defense armies, they were up to 15000+ and i have no idea why, i did'nt even have an army building except for the t1 dark matter palace thing, the only other reason it could have happened is because i had the unemployed pops set to virtual soldiers. but even then it shouldn't spawn 15k.

I have come to the conclusion that it never stopped spawning defense armies or spawned them whenever a pop went virtual soldier and then back. It could also be because there were pops being assimilated on the planet

my mod list is as follows in this load order:

Gigastructures
Acot
Carrying capacity (disabled half way through the game)
expanded stellaris traditions
expanded stellaris ascension perks
planetary diversity
Guilli's planet modifiers and featuresy
more events mod
automatic repeatables
SLEX - Stellaris list EXtender
Light borders
Pinwheel Galaxy
!!!Universal Ressource Patch
Tiny Outliner
UI Overhaul Dynamic
24 Building Slots

The planet was a size 20 gaia world (the preserve) with +6 districts and +12 districts from fallen empire planetary modifiers. The only Building where the t1 dark matter palace, t1 dark matter spire +25% growth speed thing and t1 dark matter revitialization chamber. I had the settlement for quite some time, a whole truce time to be exact.

The reason it shows -126 pop jobs on the screenshot is because i moved at lot of pops enduring assimilation (into psychic) there (which is propably part of the cause)

Another thing is it thats it seems to be starting again on a alderson segment of mine, where i built a giga fortress and the t1 dark matter bastion thing. there are currently 2k armies there.

i searched for a mod to limit the amount of defense armies on a planet but didn't find one.

And another thing is that the amount of Defense armies on the planet made it so i couldn't see my assault armies in the outliner, which allready happened again.

I fixed it by abandoning the settlement by moving all pops away from there. (including the lag at the 1st of every month) That despawned the armies, but of course it would be better for it to never be able to happen again. The lag made the game almost unplayable.