That means people who bought an Intel-based Mac Pro in 2023 will only have gotten security updates for five years after purchase. Wow.
The only people buying a Mac Pro in 2023 are people who are buying it because they specifically need Intel and they know that Intel on the way out, but they just still need it for something.
If you purchased a Mac Pro in 2023 and didn’t realize this was happening you have no business buying a computer. No one in an Apple Store is gonna push you towards a Mac Pro, it’s a very niche product.
I went to the Apple.com "find your mac" tool and even knowing what I wanted to get back, I couldn't even convince it to recommend a Mac Pro. https://www.apple.com/mac/best-mac/