Ok from pcgamer: > Always remember to back up your old save files before loading them into the newest version of the game. With the new changes to world genera

Ok from pcgamer: > Always remember to back up your old save files before loading them into the newest version of the game. With the new changes to world generation, Mojang say that new chunks generated in worlds you bring forward to 1.18 should better blend with the existing terrain in your save file. So long to big flat chunk borders in old worlds!