A release lookup allows "(user-)ratings" as part of its "inc" parameter, presumably to be used in conjunction with "release-groups" to get the ratings for the releases' RG.

For example: https://beta.musicbrainz.org/ws/2/release/63591e68-a1f5-41f6-977a-4db4ba056fd7?inc=ratings+release-groups

In the XML serializer, no ratings elements are produced under the release for such a request, so requesting only ratings is effectively a no-op:

https://beta.musicbrainz.org/ws/2/release/63591e68-a1f5-41f6-977a-4db4ba056fd7?inc=ratings

However, with JSON output, a rating is erroneously included:

https://beta.musicbrainz.org/ws/2/release/63591e68-a1f5-41f6-977a-4db4ba056fd7?inc=ratings&fmt=json

In addition, when the release group info is requested as well, that does NOT get a rating added:

https://beta.musicbrainz.org/ws/2/release/63591e68-a1f5-41f6-977a-4db4ba056fd7?inc=ratings+release-groups&fmt=json