Spotify would love to have all of the content available for everybody everywhere. Unfortunately sometimes there are various occasions that may cause some of the content to become unavailable - changes in licensing, rights changing hands, artist's decisions or agreements that are pending or can't be reached (just to name a few).
Hopefully the song becomes available soon!
If you'd like more information on this, I suggest reaching out to the artist, they possibly know better what's up!
Have a lovely day :)
SebastyRock Star 16
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.