Man, some of the comments this is getting are absolutely wild.

OP, I’m sorry this is happening to you. It must be incredibly frustrating to have people ripping off something you’ve worked on for many years and pass it off as their own work. I would be furious in your position.

I wish I could do something directly to help you but the best I can offer is to echo the best advice others have already given you: it’s time to get a lawyer. That is the one guaranteed route to get GitHub to sit up and take the action they should already have taken on your behalf.