The bug fix in https://jira.mongodb.org/browse/MONGOID-4593 was a breaking change as reported in https://jira.mongodb.org/browse/MONGOID-5279. It should be in release notes, but wasn't entered as such because when 7.1 was released we weren't doing release notes in documentation at all. (The change was documented in https://github.com/mongodb/mongoid/releases/tag/v7.1.0.rc0 which was the version it was made in, as per our practices at the time.)

Given it is a breaking change, we should consider adding it to release notes retroactively.