It's worth noting, of course, that those illicit forks of NewPipe also violate their license. If dishonest proprietary software developers don't care about NewPipe's license why would they care about FUTO's? If they really want to stop forks they can simply make their product source-unavailable, but then they don't get to claim to be "open source" or "open source adjacent."

The problem is not so much that the are forks (remember, in the free software world, forks are explicitly allowed) but that these forks use the branding of the original project and thus damage the original project's reputation. There is a tool for dealing with counterfeits - trademark - and it is a tool used by reputable free software organizations such as Mozilla and Debian. Now imagine if those free software projects adopted FUTO's hostility to forks - it would be a net loss to the free software community. Don't let organizations like FUTO sell you the idea that you don't need the freedom to fork.

Of course, even proprietary products can be counterfeited, and trademark helps stop those too.