As always, a note to infrastructure providers: HOST YOUR LIVE STATUS DETAILS ON OTHER INFRASTRUCTURE.
Of course, they won't. If they host is on someone else's then that might look bad (tacitly saying that a competitor is reliable and might be up when they are down) and if they hive off an extra copy of some of their infrastructure there will still be single points of failure either accidentally, by human error (someone somehow messing up both segments at once), or by design (possibly through management trying to save pennies when they noticed this extra bit of infrastructure on the balance sheet).
I agree with your lead statement and argued as such, but was overruled. Last I knew and understood, Heroku Status is static pages pushed out to Fastly, with the internal admin site (that does that work) running in a Heroku Private Space. If you look at the DNS, it still appears to be served by Fastly, and Heroku Private Spaces are generally pretty isolated infra, so I would be curious what the failure mode was here. But ultimately this is the fire you play with when you self-host your status site...
I am pretty sure Heroku has a Linode box or something for their status page. I may be wrong though. They may also have moved it but that would seem like an incredibly dumb idea.
I worked there and I vaguely remember something like this but it's been a long time.
If I had to guess this is probably a DNS issue (it's always DNS).
