I ran into the same issue out of nowhere with my Spotify app a few months ago- after hitting around 300 users. Apparently, Spotify has a limit [0] on their API quota for auth (around 25 users or so in theory), but don't feature the limit very prominently in their documentation.
Have you requested and obtained a quota extension? I gave up on my app altogether after a couple of weeks and seeing in their documentation "[this] review process can take up to six weeks."
Oh no, I didn't know about this. It looks like Spotify hasn't authorized anybody but me and I would have to add every user I want to add individually. I don't think that anybody has been able to use this app. If anybody really wants to try it out you can DM me on X https://twitter.com/thelukew3 or follow me there and I'll post an update when it's fixed. Maybe I'll relaunch next year. Thanks for the help.
Have you requested and obtained a quota extension? I gave up on my app altogether after a couple of weeks and seeing in their documentation "[this] review process can take up to six weeks."
0. https://developer.spotify.com/documentation/web-api/concepts...