The legs on my Avatar glitch ever since the update

So I have a Custom Avatar that was made for me and I’ve since messed about with her, mainly shaders and textures.
Ever since the update her legs glitch whenever she stops moving. They usually sit with the toes pointing inwards and when she crouches her knees would be together.
Since the update the legs have been glitching to face forward and when she crouches she spreads her legs in a very unflattering manner. I’ve tried reuploading her but the problem remains. I’ve no idea how to fix this? Can I please get some help, it’s really annoying me, I want to be able to use my Avatar.

This is how she is supposed to look.
This is how she looks.

Issue related to the rig of the avatar. This can happen due to stuff like improper rotations on the bones, the knees are “too straight”, etc.

Firstly ensure you clear bone rolls in Blender and see if that helps, if not refer to the video below.

This video should help detail the steps to ensuring the legs are setup properly. It’s intended to fix your limbs twisting but it should work for this as well.

I’ll give it a look but I’ve got nearly no experience with Blender.
I’m playing on Desktop as well
The Avatar was perfect before the update.

That’s because flawed rigs worked okayish due to bugs in VRChat allowing rig hacks or broken rigs to work relatively fine.

Now if the rig is broken or you have rig hacks on the avatar it will likely just not work correctly.

I’ve genuinely no idea when it comes to Blender, even with the video I’m at a complete loss as to what I’m doing. I don’t know what’s right and what’s wrong. I don’t want to end up seriously breaking my Avatar.

That’s why you just use a duplicate version of it? Keep the original file but make a duplicate that has all the changes made to it. You can also start at a earlier point in the tutorial, you likely don’t need to mess with the arms but just watch to see what he’s doing leading up to fixing the legs. https://youtu.be/2sfTEBAl8sA?t=2127

Otherwise though you’d likely need to either pay somebody to fix it or see if somebody (like a friend) is willing to fix it for you. I find it odd though that someone who does commissions didn’t set up the rig properly in the first place though.