A Reddit user Reeceeboii_ highlights, any time you share a song from within Spotify, it generates a unique tracking URL linked to your account. Spotify can join the dots between the sender and receiver whenever anyone clicks on this unique URL. People have allegedly noticed that Spotify has retroactively filled out the history of song shares in the Messages feature, which is possible through these tracking URLs.
knowingly not removing the trackers from links you send to people is like being a trained chef and deliberately giving your loved ones food poisoning.