Looks like a very interesting project, but maybe there's some misunderstandings about the license; from the readme:

> x64dbg is licensed under GPLv3, which means you can freely distribute and/or modify the source of x64dbg, as long as you share your changes with us.

Should probably read: "... as long as you make genuine offer of providing the source code and changes to those you distribute your version of x64dbg to."

In practice it of course makes sense to upstream changes, but there's nothing in the gpl about that.