Example:
Go to https://musicbrainz.org/release/9e42ea80-4e37-49c2-96b0-bd9bdd7c1f67
Select Edit
Go to Edit Note and see notice: "Some errors were detected in the data you've entered. Click on the tabs shaded red and correct any visible errors."

There are no tabs shaded red. The only oddity I've found is a lack of ability to add "External Links"

This seems to happen for all releases that have no external links for the release (at least in this release group).