In MB, if you call the /entity/id URL, it will redirect to the matching /entity/gid URL.
But it is broken for recording:

It's a pre-NGS code that is staying in MBS that is no longer working for NGS.

NGS has now separate track and recording ID, but pre-NGS, there was some redirection necessary or something: https://github.com/metabrainz/musicbrainz-server/commit/7acea69a042a4f50f759199fe661e736cee208a4

Example: https://musicbrainz.org/recording/272811 should lead to recording with ID 272811.
Not to unrelated recording with ID 316322 via track with ID 272811.

https://musicbrainz.org/recording/272811 should not lead to same recording as unrelated https://musicbrainz.org/track/272811

Related to lib/MusicBrainz/Server/Controller/Role/LoadWithRowID.pm / _row_id_to_gid