i have spotify premium and have been having trouble with songs becoming unplaying, even from larger artists such as my chemical romance and lil miquela. certain tracks will become suddenly grayed out and unplayable.
I just experienced this issue and managed to fix it. A particular artist (Protest The Hero) had multiple albums that could not be played. The albums and songs showed up fine but nothing happened when I pressed play. This was true on android spotify app, microsoft spotify desktop application, and the web browser version of spotify. Here's how I happened to fix it First I opened spotify in a web browser - I used chrome. Then I went to the album I wanted to play. I hit shuffle. The web application kinda crashed so I hit F5 to reload the page. After that when I pressed play on the album it worked again. I could also play individual songs and the other albums I was having trouble with are now playable. Don't know why that worked but it did lol
Availability of music on Spotify is up to the artists (or representatives) and / or their labels. Music missing can be a decision of one of them.
Music missing can also be related to a licensing problem. Licensing rules are not the same from a country to another. That can lead to have albums or songs available in some countries and not in some others. Usually when a licensing problem is solved the music can be added or comes back if it has been removed.
Spotify wants all the music in the world to stream and works hard daily to try to convince artists and labels to let all their catalog in streaming.