How release canaries can save your bacon
I'm less enthused about 'rollbacks' being considered 'normal'.  They signify something didn't go quite right with your unit/integration/qa process.  IMO there should be at least a 'mini-postmortem' to understand why it was missed even if it's in an intentional blind spot. (i.e you made an explicit decision it wasn't worth the engineering resources to get the testing fidelity needed to catch the issue earlier).  It's almost always better to catch issues earlier, even if you have super neat tooling that makes it easy to rollback.