1 - Gather two people.
2 - One of you switches to this avatar : avtr_7a0a8271-e175-4151-adc4-6af65d8a9895
3 - The avatar deletes itself because of a trail renderer with "Auto-destruct" set to True on its parent object.
4 - While loaded, the second person will see their local mirror copy be frozen in place, not responding to IK or animations UNTIL the problematic avatar is hidden or switched out of
5 - From now on, both users will see every vrcconstraint completely broken, seemingly unable to even initialize UNTIL GAME RESTART.
Note : Weirdly enough, this appears to only affect constraints used by avatars having been converted to the new constraints in unity and NOT other constraints being supposedly auto-converted in-game.
Note 2 : This discrepancy between auto-converted constraints and the rest extends past this specific issue and I've noticed many instances of avatars behaving differently with the same setup, only one being auto-converted while the other isn't.
PS : I am sorry for whoever is going to have to deal with this mess-