Yep, sorry, it’s due to the mesh being “baked” for feathers with normalizedcrow’s shader. You’ll have to check their Discord for precise instructions… you can use the existing blendshape sliders directly in Unity, though some are controlled via animation (“Body Condition” under… wherever that is).
iirc you have to go to the model in the Scene and point its Body mesh back at its original Body mesh from its .fbx, then you’ll see your changes. Then if you want your shader feathers to work right, you’ll have to rebake your mesh in normalizedcrow’s shader…
There’s a proper way for me to make the feathers “real” so there’s no more baked mesh struggles, but it only came out recently!! I don’t understand it yet, and I’m really busy ^_^;;