I specifically had to disable that via about:config in Firefox ages ago because I pressed it by accident all the time. Often while I was going through a 30 point form, only to then lose all my progress. To be fair, browsers probably should try to not undo progress like that, so you can just go forward again and get right back where I started, but I've never trusted them to actually do that. I've been burned too many times.

I can kinda get that one.