FWIW, the reason Apple has gone back to calling these builds "Release Candidate" is likely in line with much of the rest of the tech industry moving away from using terms like "master" (as in "Golden Master") due to longstanding racial connotations (the company I work for being one of them).
It's mostly semantics, in any case — the last builds before a public release are quite often called "release candidates", whether it's an iOS release, a switch software build, or any other large software product — it's standard software development terminology that has been in use by many companies for many years. There's a reason they're referred to as "candidates" — there's always the chance that a bug may be found in an RC build that necessitates a new build, and there won't always be another posted RC build before the final release (see: build increment from 14.2 RC to 14.2 release).