Qobuz removed a range of releases a couple months ago at short notice, including from users' accounts. Hopefully their catalog remains strong as it's about the only online-only store with lossless that has a wide variety of mainstream artists.
I'll also mention: Bleep.com, Boomkat, Ninja Tune (label that directly sells), Junodownload.
Yep, "Pink Martini - A Retrospective" was removed after I bought one song from it, when I click on the track in my library the error toast states "It's impossible to play this track. Thank you for trying another playback format."
But that's the whole point of buying it, mp3 is safely on my SD card, plays just fine
It wasn't explained officially. I assume some distribution arrangement changed but the artists/releases were so varied and from various labels that I can't determine the relationship. I'd bought a handful of releases there and all of them were affected.
I'll also mention: Bleep.com, Boomkat, Ninja Tune (label that directly sells), Junodownload.