Apple has two formats for URLs of specific songs on their streaming service Apple Music. Neither can be entered into MusicBrainz.

Format 1: 

https://music.apple.com/[cc]/album/[albumnum]?i=[tracknum]

The system cleans this up by removing the ? and everything after, turning it into an album link. MusicBrainz then tells the user this isn't a valid song link.
Format 2:

https://music.apple.com/[cc]/song/[tracknum]

The system doesn't clean this up, but it doesn't accept it either: "This URL is not allowed for the selected link type, or is incorrectly formatted."

While I understand not supporting format 1 if the system will clean it up into the album link, I'm not sure why format 2 isn't supported.