Similar to MBS-11537 some recordings have quite a lot of ISRCs attached. In some cases it's an indicator something is wrong, e.g. a release that was added as a standalone recording.
But in (presumably) most cases they are probably valid:
https://musicbrainz.org/recording/21bc4ba0-3b43-43b8-9702-f5f066c894e8

This is problematic as they push down other elements in the sidebar, like tags, editing tools, collections.