Leaf blocks breaking/despawning all over in singleplayer for no reason

So basically i loaded up an old world from an older minecraft version in 1.13 and for some reason the leaves in the jungle are breaking for no reason whatsoever. I spawned in and heard leaves breaking and then i saw it happen all over the map. The bad thing about this is that it's a hungergames map and the leaves are essential for the gameplay... I have no idea what's causing this. Any ideas? Also, i created a backup of the world before i loaded it up, where can i find that? I don't know if vanilla datapack is or isn't disabled, and i wouldnt know where to find it... any help?