Random objects appearing in public lots

Hi everyone,

Since a couple of Sims plays, random objects appear in random places (such as floating guitars, plants growing on roads and cups). Recently I also noticed that the GeekCon and romance festival are appearing on top of each other (while neither of them should be available at this time). All these items appear on lots that aren't editable/you can't travel to directly.

I also had some random debugg objects appearing in my Sims's household inventory after moving (some romance festival items, like picnic tables and confetti flowers)

I think my save file might be corrupt, since another save file doesn't seem to have this problem. I tried putting back other versions of the save file, but that didn't help.

I hope you guys can help me out, since I'm in my 12th generation and don't want to lose all my progress.

I've attached a screenshot of the bug.