For years, Spotify users have asked developers to increase the limit on the number of songs, albums, and playlists allowed in a user’s Library. That limit, which was set at 10,000 items, is now gone, as revealed on the Spotify Community forum.
— Soundofus.com (@soundofus) May 26, 2020
The change is now rolling out on all supported platforms including Android, iOS, desktop, and the web. You will no longer see the annoying All Filled Up notification when the number of songs in Your Library has exceeded the 10,000 figure.
However, there is still a limit of 10,000 songs for individual playlists and offline downloads across five different devices.