I constantly left mine off the charger overnight (Back in Feb. I had a 100% drop...no one, not even Apple knew why.)
Anyway, YES...I've had inconsistent drain overnight off the charger, from 1-3% to 15-20%. The my "Find My.." always seems to run constantly runs at various battery usage %. *I have 1 AirTag also.
Now with such a poor battery, battery health, I leave it on the charger overnight now. If the battery degrades faster. Well, that's fine with me. At this point it doesn't really matter to be honest.
I'm at the point, frustration level where I kind of wish the battery would swell a bit so Apple HAS TO replace this moronic flawed battery.