The official game page for Super Soccer on the Switch Online Super Nintendo service notes how this title will be removed from this digital game library on 27th March 2025 (or 28th March, depending on your location). The title is listed as a Spike Chunsoft release.
Nintendo: “This game will no longer be available starting 3/27/25 at 6:00 p.m. PDT.”
From another article (linked in above article), talking about Famicom version:
Nintendo: “The title “Super Formation Soccer” (Spike Chunsoft) included in “Super Famicom Nintendo Switch Online” will end distribution at 10:00 AM on Friday, March 28, 2025. After distribution ends, even those who have already downloaded “Super Famicom Nintendo Switch Online” will no longer be able to use it.”
Seems likely, since its not a Nintendo published game.
It is of course licensing, licenses they can choose to change. There are many games not published by Nintendo and they stay, because it has been their policy, because it has never been interesting to stop paying licensing fees for old games