I think its the gods trying to fix the bug of this guy arriving too early
So the world basically goes back to the day before thesild is killed, when he is killed before the set day that he is SUPPOSED to be killed in order to time loop. When that happens, nobody remembers anything, not even thesild. As opposed to, if thesild gets killed on the day he is SUPPOSED to time loop, he remembers everything and basically creates different universes everytime. As for thesild re-setting after the set date, maybe the gods will connects his, and her time line, so that when thesild dies, he AND Mc go back to the day before, with memories in tact, to prevent his death.
I think of it like updates. Some updates you need to restart your device and others you just download.
I am confused wtf the difference is between the world resetting and Tesilid timelooping. Iirc girlie only shows up in this specific timeline too so like she's included in the world reset but not in the timelooping. Like I'm confused how tf those two get triggered differently when both of them supposedly get triggered by Tesilid's death