Upgrading from 1.14 to 1.14.1-pre1 causes random chunks to be reset

After upgrading from 1.14 to 1.14.1-pre1 to check for performance improvements on my server, several chunks appear to have been reset or reverted to an earlier state. Will attach screenshots when I am in a place to do so, but that is definitely a bug that will need to get addressed before the actual release.