This has been policy for years. I just can't make myself upgrade to Tahoe.
From [0]:
"Because of dependency on architecture and system changes to any current version of Apple operating systems (for example, macOS 26, iOS 26, and so on), not all known security issues are addressed in previous versions (for example, macOS 15, iOS 18, and so on)."
The explanation doesn't make much sense here, as the patches exist, they are simply being made available only for the subset of devices. Some of the listed vulnerabilities aren't even in the OS itself, but in the apps like Books, Mail and Messages.
