Choosing/setting an own/downloaded mc skin isn't working on Minecraft 1.19.71

I wanna use my old & previously made skins that I created & It's just didn't work.

 

I'm trying to download a random skin from "The Skindex" it's just straight up not working.

 

But before 1.19.71 it's just possible to change skin. How the flip this happened?

 

I really need my skin now. I don't want any waits just to stake an update after 2 weeks of another update