I’ve run Kubernetes since 2018 and I can count on one hand the times there were major issues with an upgrade. Have sensible change management and read the release notes for breaking changes. The amount of breaking changes has also gone way down in recent years.
Same. I think maybe twice in that time frame we've had a breaking change, and those did warn us for several versions. Typically the only "fix" we need to apply is changing the API version on objects that have matured beyond beta.