There isn't any justification for the 6th to 7th to 8th gen of intel core, at all. They're the same CPUs, just faster/more cores.
https://twitter.com/dwizzzleMSFT/status/1408539533465985024
"Seems like you are assuming there is a specific security feature that defines 8th gen as the CPU floor. The floor is set for a range of quality, performance, support, and reliability reasons to ensure a great experience."