In one of my old save, my sims house became a Nightclub even if they still live there and one the map, it seems they now posed it as business. It happened after they came back from the Magic Realm.
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Ideas
Did you ever change anything about this lot ? Was it a nightclub at some point ?
Do you have a backup from before it happened so you can try again without CC to see if it happens again ? You should be able to just sell it and change back.
There's another thread for this but I can't find it atm.
I try with my oldest backup, it was the same problem, when I came back to the house with my sims, it became immediately a nightclub.
I have been able to sell the lot and change it to house again and for now the problem didn't come back so I cross fingers.