Connor McNamee
Comments
From your picture there it looks like the chunks have been corrupted. This has happened to me on a realm. I don't really know how to fix it, I would try making a copy of the world? On the realm I played on that had this issue if you caused enough lag the realm itself would crash and refresh restoring the corrupted chunks. Usually entering the corrupted chunks and throwing random items into it (They will disappear, so be careful) will cause enough lag itself. But that's just my experience and limited knowledge about the bug.
From what I've seen this bug is usually caused by having a lot of data saved onto the game (Worlds, resource packs, behavior packs, etc.). An easy solution for now would to delete any saved data you don't need such as empty worlds and broken addons.