I listen to a workout playlist on shuffle frequently while training, while slowly adding new music to it throughout the year.
Like others have mentioned, Spotify has completely stopped recommending new music for years now. Even if I start a song radio from a song I've never listened to before, Spotify immediately just starts playing songs from my current year's workout playlist. That is not the behavior I want. Yes, I listen to that playlist a lot, but when I'm not listening to that playlist, I'm trying to find new music. It seems really obvious that that would be the expected behavior, to me at least.
This has a lot to do with your present listening habits, unfortunately. 7 years in, I still get new stuff in discover weekly, though there are also a good deal of repeats which are frankly "discoveries" as far as Spotify is concerned, but nothing new from my perspective. Basically, Spotify is also recommending I listen to stuff I used to listen to a lot before I started using it (and could therefore afford to listen to more than just whatever was loaded on my phone at the time)...
Like others have mentioned, Spotify has completely stopped recommending new music for years now. Even if I start a song radio from a song I've never listened to before, Spotify immediately just starts playing songs from my current year's workout playlist. That is not the behavior I want. Yes, I listen to that playlist a lot, but when I'm not listening to that playlist, I'm trying to find new music. It seems really obvious that that would be the expected behavior, to me at least.