A single incident means 1.1.1.1 is no longer reasonably stable? You are the unreasonable one
When DNS resolver is down, it affects everything, 100% uptime is a fair expectation, hence redundancy. Looks like both 1.0.0.1 and 1.1.1.1 were down for more than 1h, pretty bad TBH, especially when you advise global usage.
RCA is not detailed and feels like a marketing stunt we are now getting every other week.
Your own "anecdata" shows how catastrophic DNS failures are and why it's justified to expect 100% uptime with proper redundancy. Too bad you had providers not architecturing properly this key part of their infrastructure to the point you had to build your own solution.