So, I had a problem with mods beforehand, I found and removed the mods (my sims were resetting while exiting carpool) and now I have another problem:
I entered my other family's business, and when I did, I couldn't talk to the employees, my sim would instantly reset. Okay, maybe I just needed to leave the lot?
I went to leave the lot and when I tried doing so... all the sims present on the lot died. A community lot, it basically became a graveyard. All the graves are the golden aspiration graves.
I've never seen this happen before, anyone has any idea of what this might be?
EDIT: Apparently, my sims are resetting when trying to interact with any sim but only when I click on them.

Okay then - it may not actually be a mod, but it is probably cc.

I had sims resetting once when I had two hair meshes for the same hair (one original, one fixed) in my game.

I also had sims resetting due to default replacements for clothing (I still don't know which default caused it, I just removed everything. I knew it was in there because the game worked well before I added those).

Sims are not actually supposed to die on community lots as far as I know (I may be wrong here) - but I guess it is possible on owned businesses. The only thing I know causing sims to just die is a plant or herb or something, if it is on the lot, sims can just die.

So I would advise !. make sure you have the essential mods (it is listed here on the forum under a sticky post) - it solves a lot of problems.
Then it may well be time for a 50/50 - it takes a bit of time, but it is, as far as I know the only thing that really works.

Good luck.