When I was made aware of a length discrepancy while merging two recordings I went to investigate where the lengths came from and how/when they were set.

The first thing I did was look at the recordings themselves, then the editing history of each recording but to my surprise no length info was submitted nor could I see an edit that added them.

Turns out the lengths were set by a disc ID. If there was a change to the mediums (tracklist) it would've shown in the recording history. (Example)

It probably makes sense to include length changes due Disc ID in the affected recording's history too.

https://musicbrainz.org/recording/cdb6c4d9-4c13-4d3f-8786-30b28395244a/edits
https://musicbrainz.org/release/b78c0e5c-c4f2-4f12-95a9-36f9dff74169/edits

https://musicbrainz.org/recording/afaa1cbe-19e0-4356-9e26-7f77130efbb0/edits
https://musicbrainz.org/release/0aa77205-e22c-4527-a64a-fe5d4ad628f9/edits