I left spotify around two years ago for a self hosted option (I mostly use navidrome+feishin). Music discovery was a concern for me as well, but then I realized that I didn't like the idea of spotify curating which music I discovered. So far, this is what has worked for me:

- Actually listening to the music I have now. I think the art of listening through full albums has slowly died, but there is so much music we're ignoring because we just listen to Artist's top tracks.

- Word of mouth. Asking my friends what they listen to. This is a way that people used to discover music and I've found so much good music this way.

- Bandcamp. Bandcamp is SUCH a good way to discover new music. You can listen to the music in app, there are great articles and you can actually support the artists!