entity texture alpha channel

1.19.2:
I made an player clone entity that renders with the HumanoidMobRenderer and uses a players skin, but all see-through pixels arent seethrough, they are plain colored. I found out that maybe the problem is in the HumanoidMobRenderer or Mobrenderer. please help making the renderers use alpha channel

(and I know there already are similar topics, but there are only answers like "it requires coding" and I want to know what I have to code)