@Contargv Please test with no mods or custom content at all, as in, move the Mods folder to the desktop and delete localthumbcache.package. You can use "save as" to rename the save so you're not overwriting the original.
If the game still crashes when you try to save, please start a new save, for comparison's sake, and let me know whether you can save that. If it works, let me know how large the original save is. You can see it in Documents > Electronic Arts > The Sims 4 > saves. Sort the files by modified date to tell them apart.
If you can't save your progress in a new save either, please let me know what antivirus you use and whether OneDrive is running on this computer.