Chunky is known to cause LODs to turn into swiss cheese and bloat up world size, as can be seen in the attached screenshot.
We recommend you enable "Distant Generation" in Distant Horizons' settings and wait.
If you actually want to pre-generate vanilla chunks along with LOD data, disable Distant Horizons, wait for chunky to finish, then re-enable Distant Horizons.
Please upload the file to mclo.gs instead of sending the raw file. This makes reading the contents of the file a lot easier and improves the chances of you getting the help needed. After uploading the file, click on