I haven’t ever seen deer in this neighborhood, but looking through events from the past day I see a bunch of Pet-tagged rabbit videos, and last week a Cam v4 recorded a fox in the backyard and tagged that as “Pet”.
I do think that Wyze’s AI model gets periodic revisions, so that could be a factor. A few months ago, a bunch of users (including me) were reporting a spate of “Gunshot” detections when we weren’t actually under fire (at least I hope not). Wyze apparently resolved that at some point. I know there have also been calls for expanded detection/identification capabilities so that every quadruped isn’t tagged as a “Pet”, so maybe they’re working on something like that, like better species differentiation. They announced Bird Detection for Battery Cam Pro with a recent app update, but reading through that topic it seems like that isn’t yet performing reliably. Perhaps after they get the kinks worked out of that they’ll refine the “Pet” thing even more. I’m really just speculating at this point, though.