So I’m not the developer, just some random dude on lemmy. But I have had similar issues with the Navidrome native UI playing large playlists. Actually, I’ve had issues with it just loading unusually large box sets. I tried to load up a 75GB box set (idk how many discs, but a lot) and the native UI can’t do it. Feishin can do it and so can Arpeggi, Navibeat, Play:Sub and even Music Assistant using the Opensonic plugin. But not the native UI.

I use Feishin to manage all of my playlists. It’s the best playlist manager I’ve ever used for any music service.