Nadia I also use this kind of functionality to track books that I have received from publishers, as gifts or as purchases, but I like to track when I have unhauled something. Currently I use tags to track that, but there is an inconsistency in the functionality. if I haven't read the book before I unhaul it, then it looks live I've never had it, because I end up removing it from my tbr. but I agree with OP that there is no way to track that I once owned it and do not own it any longer.

aftereliza bishopofsinnoh Do you all want almost something like a built-in 'previously owned' feature that you're prompted on when you un-mark something as 'owned'?

Nadia Yes that was the kind of thing I was thinking (still with the option to actually just remove from owed without adding to previously owned in case of misclick)