Notepad++ is GPL, and this fork has followed the rules of that license.
Other GPL projects have unofficial forks that didn't change the name or logo for the software in the process, and it mostly seems fine. FreeBSD ports are probably a good example of these in the wild.
Listing the original author as an author of the port is a requirement of the GPL, and the language used on this website makes it clear that Dan is the original author of the Windows release, and not the developer of the Mac release.
The only thing I see as an issue here is how the author of the port, Andrey, has failed to directly indicate that this is an unofficial port anywhere on the website, and is promoting this as if it were official. He does seem to be some engaging in some shameless self-promotion, and I understand how the open source community would not appreciate someone vibe-porting a popular GPL tool, and then acting like they own part of the official project now.
In that respect, I do see a trademark violation.
> FreeBSD ports are probably a good example of these in the wild.
FreeBSD ports are nearly always tiny patches on a project together it to compile on that OS, and look for its config in /usr/local/etc instead of /etc. It is the original software plus minimal tweaks. Linux distros do the exact same thing. When you install a Debian package, you’re getting Debian’s patched version. Same for RedHat, Homebrew, and nearly every other package manager.
The fork we’re discussing here is a rewrite of the original in a different language while still calling it the original name.
Trademark violation is the problem. It is a sufficiently significant problem.