Some players are unable to break/place blocks in certain areas

Hello! I'm playing on a exaroton server (1.18.2 on 8gb) with a modpack and everything was working fine for days. But today when some of the players logged in they couldn't interact with any blocks in some areas. At first I was able to but then I also couldn't interact with the blocks in the same area, spanning multiple chunks. Spawn protection is off, and the area is far away from spawn. I am OP'd and they are not, and we're still having the same issues. I've tried restarting the server as well and it's still the same.