kitlith
In short, ignored bones on an avatar still render in the impostor.
While revisiting and attempting to work-around a previously reported bug (linked below), I decided to try ignoring the ears and tail on my avatar, and do nothing else.
I first tried to do this with a VRC Impostor Settings component on the root of the avatar, and when that didn't work, I tried putting components on the head and the tail.
Specifically, I expected the ears and tail to disappear from the impostor entirely. Instead, they stayed visible.
Avatar ID: avtr_4e0dcf4c-88bb-463a-83ff-ecfd491067a1 version 10.
Other bug -- potentially related, if the reason it duplicates is
because
it fails to ignore it: https://feedback.vrchat.com/impostors/p/extra-child-transforms-on-vrcimpostorsettings-appears-to-duplicate-instead-of-re