I have used this avatar for a very long time, and nothing was wrong with it until the "Drone Update" officially came out. I have tried multiple versions of the avatar as well. I have also asked friends who use the same avatar to test it, and it was always breaking. However, some people can see the bones misbehaving and some see it normally. Not sure what the issue here exactly is, but it seems like animated physbones tend to break now.
Avatar ID: avtr_fabc9caa-9cdf-474e-920d-c9b54958bd9f