That isn't really backlog refinement though. That is when you start actually doing the task and you realize that plan A and plan B of how to implement the fix

That isn't really backlog refinement though. That is when you start actually doing the task and you realize that plan A and plan B of how to implement the fix or whatever can't work, and fixing it will necessarily be much more time intensive and some sort of plan C or plan D. Often this happens when you go to start changing code and you see how badly the tests blow up on you or something like that.