> (which "sits" between RHEL and Fedora in terms of "stability" as I understand).
There is no meaningful upstream link between Fedora and RHEL after a RHEL release has been forked off, so it doesn't make any sense to say that CentOS Stream sits between Fedora and RHEL.
Basically: Red Hat takes a Fedora release, heavily tweaks it, and makes a new version of CentOS Stream. After hardening, that version of CentOS Stream then becomes the basis for a new major version of RHEL. Thereafter, that version of CentOS Stream is the upstream for "minor" releases of RHEL.
Patches which are destined to land in that release of RHEL, go through the standard testing process, and land in CentOS Stream (aside from embargoed security fixes that hit RHEL first, then Stream). It's the one and only "direct" upstream of RHEL, and it's a very close upstream. Closer than, say, Debian Testing and Debian Stable. It's more like if you had Debian Stable and then there was some additional variant of Debian which just ensured that everything apart from security fixes was held back until fixed-interval point releases.
This isn't true. Firstly Fedora is always the start of the next version of RHEL. Secondly even for the current RHEL all changes go upstream first, which means they go into Fedora. Thirdly there are some packages which are rebased to Fedora every minor RHEL release (I know of the mingw packages, and a lot of the virt stack, but there are others too).
There is no meaningful upstream link between Fedora and RHEL after a RHEL release has been forked off, so it doesn't make any sense to say that CentOS Stream sits between Fedora and RHEL.
Basically: Red Hat takes a Fedora release, heavily tweaks it, and makes a new version of CentOS Stream. After hardening, that version of CentOS Stream then becomes the basis for a new major version of RHEL. Thereafter, that version of CentOS Stream is the upstream for "minor" releases of RHEL.
Patches which are destined to land in that release of RHEL, go through the standard testing process, and land in CentOS Stream (aside from embargoed security fixes that hit RHEL first, then Stream). It's the one and only "direct" upstream of RHEL, and it's a very close upstream. Closer than, say, Debian Testing and Debian Stable. It's more like if you had Debian Stable and then there was some additional variant of Debian which just ensured that everything apart from security fixes was held back until fixed-interval point releases.