EDIT: You mention this with archive.org links! Love it! https://mrshu.github.io/github-statuses/#about
That's not at all how you measure uptime. The per area measures are cool but the top bar measuring across all services is silly.
I'm unsure what they are targeting, seems across the board it's mostly 99.5+ with the exception of Copilot. Just doing math, 3 (independent, which I'm aware they aren't fully) 99.5 services brings you down to an overall "single 9" 98.5 healthy status but it's not meaningful to anyone.
Copilot seems to be the worst offender, and 99% of people using Github likely couldn't care less.