Not sure when this started happening, but it happens in the current beta 1442 and is also present in stable 1436. Physbone components when enabled the physbone almost almost acts as though it was pointing directly upwards and then flops downwards. This seems to affect all avatars, regardless of whether I've made them or not. It's particularly noticeable on avatars that have tongues that open with a particular gesture. Some avatars, it looks especially bad where the tongue will even get stuck in the roof of the mouth momentarily.
Heres a public avatar that has the issue present (do double rock and roll activate to activate the gesture): avtr_d756971a-6749-42be-8eb8-872570f57a1c