*not only Spotify
They had plenty of problems from people abusing their system to steal listens from actual artists.
Their system is basically "one big bucket of listens" - if your song gets listens, you get money. So if you pay your sub, and listen to say 5 niche musicians only, it still all goes mostly to the most popular songs.
Now you might already notice the flaw here - if you say, make a bunch of bots that just listen to songs to boost their revenue, not only your sub doesn't pay artists you listen, but also to fraudulent ones.
Then there was problems with using fake collaboration tags, AI music to hijack artist profiles, and few others.