That is what we call a retcon. How did he survive the other loops then.
I am pretty sure that is why they got all up in her grill later for interfering. "Y U NO LET US RESET"
Now that I think about it, I have forgotten what it is, that exactly causes the timeline to reset in the first place. Just because Ragna and Nu jump into the past shouldn't matter to the present timeline. I guess it is Take-Mikazuchi, but that always looked like it was just going to blow up the city only.
However, it's an NOL weapon so it's possible Hazama was using it for some reason. I forget.