Remember this very old tutorial of mine? And the observations I make every now an then?
Well, The Sims 4, at the current version from EA, is corrupting a few saves due to a bug still to be fixed.
If you still follow my advice, from time to time, you have at least a (not so) few saves to roll back to, if the worst happens.
Backup is always something you should do periodically, as usual. 😇
It is good advice not only for Sims but any other game that supports "saving as" or backing saves...