Made a skyblock server for friends, had unwanted world generation

so i was playing on a skyblock server with some friends of mine, installed a regular skyblock world onto my server slot, and we played. Everyone got off for the night, then the next day when i got on before everyone else, i noticed that there was regular world gen off to the sides of where we were making base at. It wasnt there before and i didnt know what to do, so i quickly hopped off the server and shut it down before i loaded in too many chunks before i could try to fix what was happening, but i couldnt find any way to stop this unwanted world generation from happening and i have no idea about what to do- only option im seeing is undoing all 7 hours of grinding on this world- which i obviously dont wanna do-

it is on- i didnt think about what that would do- but thank you so much, now ill just have to re-download the world and remove all those chunks that were added in some kind of world editor software- but thank you so much