Yes, you can. This is something everyone gets mixed up. RHEL is built from CentOS Stream sources. The changes Red Hat made to RHEL source distribution mostly

Yes, you can. This is something everyone gets mixed up. RHEL is built from CentOS Stream sources. The changes Red Hat made to RHEL source distribution mostly just make it more challenging to reconstruct an entire build of RHEL from CentOS Stream - because you would have to map backwards from all of the different versions of sources available in CentOS Stream to the exact versions that a particular version of RHEL happens to use. But at the scale of any individual project, it's trivial for any upstream community to just look at the latest CentOS Stream sources for one particular package, if they want to look at which patches Red Hat is applying. There are no legal or contractual restrictions on this whatsoever. This is setting aside the fact that most patches are backports from one upstream version to another, and bugfixes that get submitted "upstream first" to begin with, which makes the whole discussion kind of moot. The typical scenario for a net-new bugfix would be that a Red Hat employee submits the fix upstream and gets it reviewed and merged by said upstream months before it ever sees the light of day in RHEL, so upstream maintainers would never need to look at the RHEL sources in the first place.