That actually looks like a sync conflict. If you (or your add-ons) make changes on one device while you also have unsynced changes on another device, it can leave cards in an inconsistent state like this – both studied and not studied. See this prior post for causes/solutions: Scheduling differences between Anki desktop and Android - #4 by Danika_Dakika .
Since you’re using FSRS, there’s no need for you to change the interval as well – in fact, FSRS controls that.