I am not aware of any changes regarding mapped drive letters. I know of a fix for UNC paths, which was in 1.20.2 or 1.20.3.
Nothing of those measures listed above has an effect on the size of the Plex data folder
If you want to relocate the Plex data folder to a different drive letter, follow these instructions: [HowTo] An extended guide on how to move the Plex data folder on Windows
