This is not an issue with computer files, it seems to be connected to a seed. It seems to happen mostly to caves, though trees, terrain, structures, etc. can also be affected. Whatever is generating seems to stop dead in its tracks if it tries to generate in a specific chunk. A seed will always have this happen at the same location every time. The screenshot was taken at x=400, y=32, z=-208, and the seed is -676194426.

For some reason the 'affects versions' thing only included 1.14.60 as a choice, even though the latest version is 1.15.2, and the latest snapshot is 1.16-rc1