A superficially modest blog post from a senior Hatter announces that going forward, the company will only publish the source code of its CentOS Stream product to the world. In other words, only paying customers will be able to obtain the source code to Red Hat Enterprise Linux… And under the terms of their contracts with the Hat, that means that they can’t publish it.
It could be argued that is also a restriction disallowed by the GPL (in my mind any terms that bring negative consequences for expressing your rights given by the license are restrictions), but at that point it’s really beyond my expertise on this subject. I’m not sure if the GPLv3 even defines this at all - maybe Red Hat is banking on that ambiguity.
They might also be banking on GPLv3 contributors being unable/unwilling to take them to court. The Linux kernel is GPLv2, and its contributors are probably more of a legal threat than anything else in RHEL.