Does anyone have info regarding swapping meshes in Unity that you decimated in blender? For vrchat avatar

Hi all! I transferred my fbx to blender because I had over a million triangles on it and I was trying to optimize it. I used the decimate tool and figured out how to ensure there were bones/vertices and that my export settings were correct.

However when I import it back into VRchat, the meshes look invisible. I even tried adding the new edited fix to the scene and copy and pasted the Skinned Mesh Renderer component info onto the old fix. But for some reason it always turns invisible. I have tried changing the root bone in the window but that doesnt help. I also tried increasing the detection window thing and that didnt help. I cant find info on YouTube.

Does anyone have info or a link to an article explaining how to swap meshes correctly? Thank you so much! :)