I actually sent a suggestion/complaint to Google regarding their recommendations. If I start a radio station based on e.g. a 2009 indie pop song I'll mostly hear songs made around that year, usually like 2006~2013, with newer songs just absent. If I make a station based on a 2019 indie pop song, for the most part it's all the same bands as the 2009 playlist, it's just that the songs are more recent. I don't really like this because it forces me into a time capsule instead of just playing indie pop songs from any decade.