I just downloaded and have been loving this. It loads pretty quickly, navigation is intuitive, and I'll finally stop forgetting that Nebula exists because it'll all be in my one big subscription feed.
Since I'm new to moving over to open source, I want to ask the veterans: is this as incredible as it seems right now, or is there something I'm missing?
Seems weird to be against the one major selling point of free and open source software (anyone can fork it and scratch their own itch), but then claim to be open source.
Anyway, to each their own, I'm glad you like it!
Seems pretty natural for me considering one of the points of open source software is to try and get away from trackers malware and bloated ad experiences so you can see directly what you are running, making sure your product is not able to be abused in that way promotes more open source initiatives while allowing the owners to make sure any changes jive with the original intent of their open source software. You are free to modify all you like so long as you don't distribute a forked version with ads, malware or trackers. They cover this very clearly.
I think the main point is, this makes it unavailable in F-Droid and everyone else unable to build upon, use or adapt it for their own use-cases except for the specific ones outlined by FUTO. It's source-available software. Not free software. And it has other downsides, too. Once YouTube starts cracking down on third-party apps and the companies behind it, it's gone for good. yt-dl has demonstrated free software offers more resilience in those cases.
And I'd argue it's ineffective. Having a license forbid malicious use will only stop the honest people from using it. The bad players will probably not care. But that's debatable.