Github ignored licenses for this project and included code from all publicly-accessible repos. They claim it's not copyright infringement and you can e.g. use code from this AI trained on open-source repos in closed-source projects.
It's not clear to me how it is copyright infringement if the generated code is truly new. Of course, if some code output is very similar to existing code, then it is obviously copyrighted.
When you read code from an open source GPL repo and are inspired by it to write your own code, it's obviously not copyrighted.
Also, some people explicitly avoid reading codebases to avoid duplicating by mistake some copyrighted code.
Not sure if this is true but I heard that it used to be forbidden to Microsoft developers to read open source code.