How to overwrite OIDC groups per application?

[Caligatio]

I have been using custom Scope Mappings for a while now to create a custom set of groups exposed via OIDC depending on the application. Recently Nextcloud notified me that I was added new groups which are the entire list of available groups in Authentik.

I did some digging and it now looks like returning a custom groups key in the Scope Mapping adds those groups to the groups value returned by Authentik by default rather than overwriting it. Per #14100 and my prior experience, I thought Scope Mappings overwrote the groups key?

Did something change with Authentik?