Is your feature request related to a problem? Please describe.
I have been using OptiFine for a while and the OF developer has fixed the issue with capes animation being too jittery MC-127749

Describe the solution you'd like
It would be nice to see this fixed in near feature, it seems, Mojang doesn't care at all about it

Describe alternatives you've considered
Well, clearly OptiFine has fixed the issue, so it's an alternative.

Additional context
Sodium seems like a super good replacement for OF, with my setup it's pretty much OK toi play 1.16 with OF but FPS is too low for streaming, with Sodium I get areound 400-600 FPS which is incredibly cool and this issue in particilar makes me feel really annoyed tbh, not sure if it's even possible to fix via mod but it would be a nice fix!