Minecraft skin has black stripes?

I recently uploaded a new skin, but the problem was that my skin has black stripes on the back arms.

I have already tried 30 skins, but none of them worked without the bow.

Can i do anything?

There are the normal arms and the slim arms. Switch to slim and then try again.

Think that you either chose the wrong arms or the skin is formatted incorrectly.

Here is a page to try out, just test lean and normal, then you will see where the error is anyway and can correct it.

https://www.minecraftskins.com/skin-editor/

You have to change your skin to slim / wide.