u/Antique-Chemical-654

So i started a hardcore world with a friend will i was on vacacion using the essential mod not a server since i was on vacacion i was playing on my old pc then i transfered the save to my actual pc its the good seed i still have my loot and i am still at the location i logged of last time but the world just got a "reset" our base was in a cliff but the terrain just got to the way it used to be before building but ours dogs and happy ghasts are still here.
then i told my brother to try to join the world on my old pc and it just work fine, do you guys have any idea how i can fix that please ?
the version is 26.1.2 with fabric loader