todsacerdotiGitHub's Historic Uptime
It’s biaised to show this without the dates at which features were introduced. A lot of the downtimes in the breakdown are GitHub Actions, which launched in August 2019; so yeah what a surprise there was no Actions downtime before because Actions didn’t exist.
This is the real questionable part of the graphic. It seems that no-data pre 2018 was just considered 100% uptime (which is hardly historically accurate).