Yet, if you're audited, it's just a series of IDs and numbers, nothing identifying there...Right?
If you ask Spotify for your data dump, you'll notice in a lot of the .JSON files the information is encrypted such that you can't understand it (it's just numbers). It's impossible to say whether it's actually stored like this or if they encrypt it before they provide the archive to you.
Meta data is almost impossible to legislate against, and as far as I can see, is entirely legal to collect and use as you see fit.
How many people in the world are on hackernews, named "lopis", use Firefox 65, have an IP address in $country, use this screen resolution etc etc
Easy enough to identify who you are.