In general any usage of the LB Radio for an artist but excluding similar artist is totally broken; i.e. it mostly recommends low quality tracks, live tracks, etc.

https://listenbrainz.org/explore/lb-radio/?prompt=artist:(radiohead)::nosim&mode=easy

https://listenbrainz.org/explore/lb-radio/?prompt=artist:(radiohead)::nosim&mode=easy

One would expect an artist radio to just offer a shuffle of the popular/mainstream artist tracks. Obviously not just the Top 5, there are other endpoints for that. But at least not +80% live tracks not representative at all to the artists work.

I suggest to try with any artist, it's always the same (even if you add multiple artists with such option). 'nosim' option breaks playlists unless you add more things.

Furthermore, the problem is worse when playlists are being filled with youtube videos, ads, interviews, ...
https://tickets.metabrainz.org/projects/LB/issues/LB-1460?filter=allopenissues
https://listenbrainz.org/explore/lb-radio/?prompt=artist:(radiohead)&mode=easy

Also an artist's playlist should have more than 4 tracks.