Hi @atari604 and welcome to the Community! 🙂
I just tested this function on my iOS app to see what's up and this is how it worked for me.
1. I started an artist radio and clicked the thumbs up on the songs I liked.
2. Those thumbed up songs were moved to the "Liked From Radio" playlist, but not the entire artist.
Just for reference, I am using the app version 8.452.796 which was updated this week.
I hope this helps! 🙂