I’ve done it multiple times without much effort. Or skill. Really it was a skill issue and I tried things that I thought would work but apparently don’t.

I screwed up jj a few times while picking it up, but jj’s undo command made that trivial to go back and try again. With git? I know a lot of things can be undone but I can never remember how to do it!

I'm glad to hear you never encountered the kind of quagmire that can occur around e.g. non-trivial conflicts while rebasing a chain of git commits. On large enough codebases, those can be common.