Good to see a detailed summary. The frustration from a customer perspective is that AWS continues to have these cross-region issues and they continue to be very secretive about where these single points of failure exist.
The region model is a lot less robust if core things in other regions require US-East-1 to operate. This has been an issue in previous outages and appears to have struck again this week.
It is what it is, but AWS consistently oversells the robustness of regions as fully separate when events like Monday reveal they’re really not.
>about where these single points of failure exist.
In general, when you find one you work to fix it, and one of the most common ways to find more is when one of them fails. Having single points of failure and letting them live isn't the standard practice at this scale.