How exactly is that proof? That's just replacing the usage of one library with another.

You can go and see the original repo here: https://github.com/dessant/label-actions And the "copied" one here: https://github.com/hramos/label-actions

I didn't look too much at the code, but at first glance it doesn't seem copied. The API might be the same or similar, but that's a different discussion, as is for taking the same name.