Some would simply call it an evolution of style, and others might call it a sellout. I’d like to hear your examples of musical acts that changed so radically over time that you’d consider it a sellout.
My example would be Jefferson Starship. Their first album was “Blows Against The Empire”, which was about hippies hijacking a starship. https://www.youtube.com/watch?v=HzclibWeXM8&t=1126s
Grace Slick was the first person to say “motherfucker” on television when performing their material.
They went from that to shedding personnel, renaming themselves “Starship”, and making pop music. https://www.youtube.com/watch?v=IDI2WQJyE7I
What are your before and after examples that you consider a sellout?
Prog Genesis was so weird to discover in my teens. I was used to the 80s Genesis from MTV.
Shapes was my first album, when I was 15. Then Three Sides Live, then Seconds Out, then anything I could get my hands on.