@wrigonato It seems to me that those character were most likely temporary/weakley free ones; There is a new system that Popcap implemented in this title where you get a couple of character every week. Once this "trial" is over you'll obviously lose access to them unless you managed to unlock them via sticker shop. I imagine that all the experience gained during the free access is saved until you are granted full access.
I lost a bnunch of plant characters yesterday. I got them from the sticker shop and paid a lot of coin for them. You can see ? marks in the detailed stats where their names used to be. I have attached a jpg of the Citron. The Level 10 wa the Party Citron.
