Ideas
i’ve also got this problem but worse while rebuilding the worlds in a new save file. i’m going to experiment a bit more with it, but so far i’ve got:
a residential lot placed for the gallery over The Rouge Note in Hordhaven — i moved a sim in it, entered live mode to start a business there and when i opened the build mode to add a ticket machine i discovered that this residential lot reverted back to lounge type;
a wedding venue placed over a lounge in Tartosa — when i opened the build mode for the second time, the lot type reverted back to lounge;
a residential lot placed over the existing wedding venue in Tartosa — reverted back to a wedding venue.
several tiny home residential lots reverting back to just residential, i think all of them were placed over residential lots.
I also think I had at least one community lot revert back to residential but i cannot remember which one and where.
i also have multiple lots placed without this issue, and i think changing the lot type (and probably also bulldozing it) before placing a lot from the gallery prevents the issue.
i checked the save file in sims4studio — these lots have correct lot types in Zone Object files, but their original lot types in Save Game Data in Zones info, unlike other lots that don’t revert back to their original types.