I'm not sure the best way to explain this, but Spotify's catalogue seems to consistently "shadow" itself, where an album is re-uploaded or something, but the old one is still there.
An example: I have a few "liked" songs by Bob Marley, on this Exodus album: https://open.spotify.com/album/655KljKIXl42fiNDMKivbY?si=8i54w9vpTK2VHlwkHMzwsQ
That's also the album that you find if you go directly through Bob Marley's "Popular" songs.
However, if you browse his albums, "Exodus" just isn't there. There's "Exodus (Deluxe Edition)" that presumably serves as a replacement, as it's "Exodus" plus some other stuff. Sometimes, there's not even a discernible difference.
I find this very annoying, I have a lot of "liked" songs, and songs in playlists of mine, which are no longer reachable by browsing the artist's catalogue. It makes it hard to stay organized, when over time the the media I interact with can spontaneously disappear from the UI, with vestigial access points (like playlists and the "popular" list).