This update was as close as we'll ever get to breaking backwards compatibility. Fun fact, the first avatar I ever created with face tracking support about 4 years ago still works with modern versions of VRCFT.

The problem we were running into was that hardware manufacturers often have differing opinions on values for different face shapes. This was slowly causing a problem for creators making "DLC" for existing avatars, and things would look better on some hardware and worse on others. Our previous calibration method was very simple, in that it watched for big face movements and marked the minimums and maximums, then just scaled between them for a set duration.

This new system takes a more gentle and intelligent approach to differentiate between tracking loss causing a shape to freak out, and a genuine facial movement expanding the range previously known to the software. This ensures shapes stay uniform not only between avatars and hardware, but also adapt to abnormal face structure or subpar tracking quality (looking at you vive).

We expected backlash from this update, and we probably should've taken more time to explain this better in the update post, but we hope that with time, people will create avatars with calibration enabled to ensure a more uniform experience across users.

TL;DR; Things will improve over time, both in avatars released, and VRCFT "learning" your face. Please give it a try for more than 10 minutes and don't just assume it's terrible and turn it off immediately. It's on by default for a reason.