A lot of android apps made using YouTube music api stopped working. Like vi music, ri music , innertune is no longer working. Google is trying their best to stop them. But you can still use them if you log in with your Google account.
If you have to reverse engineer an API you're effectively using a private undocumented unsupported API. Why would you be surprised that a private implementation has changed without notice?
Idk if it surprises anyone, really. Besides, given those apps are trying to eat yt music's lunch, it was more or less a matter of google considering them popular enough to take actively hostile measures... So, unsustainable in the long term, I guess.