alt Hacker NewsI think 2 things may be combined here.
'GitHub Enterprise Server' is hosted on your own resources, not their cloud. It makes sense that it wouldn't have the same downtime as their cloud, but that's hardly relevant.
'GitHub Enterprise Cloud' is their offering hosted on their own resources and what I suspect most enterprise customers use. It's what I at $extremelylargecompany use. It follows the same uptime/downtime as their public non-enterprise offering.
No if you use GitHub Enterprise Cloud with data residency then you are on separate infrastructure. Here is the status page for the US enterprise cloud data residency https://us.githubstatus.com/posts/dashboard (which funny enough is reporting an issue atm).
You can tell if you are on the github enterprise with data residency because you will access github at a GHE.com domain rather than github.com. It definitely has better uptime than the public cloud but is not without its own issues.