In Desktop Mode, the avatar's legs suddenly move forward or bend into unnatural positions when entering the prone pose.

The legs sometimes become severely distorted before the avatar transitions into the intended prone position.

Steps to reproduce:

Launch VRChat in Desktop Mode.

Use an avatar and switch to a crouch or prone pose.

Observe the position of the legs during the transition.

Expected behavior:

The avatar should transition smoothly into the pose without unnatural leg movements.

Actual behavior:

The legs move to incorrect positions, sometimes folding or twisting unnaturally.

Additional information:

This issue has been occurring for several months.

It affects multiple avatars.

It also occurs with sample avatars that do not have custom pose systems installed.

It occurs in multiple worlds.

All screenshots were taken using sample avatars provided by their respective creators.

Screenshots are attached showing the issue.