I am having the same problem with huge pdf print sizes.  The same client in 2018 had a Form 990 file size of 1.774 MB and in 2019 it print the pdf with a size of 7.046 MB.  There was no change in the client forms and associated schedules in 2019.

When I print the pdf audit space usage report the "content streams" went from 139,704 bytes in 2018 to 5,978,837 in 2019.  

Something has changed about how ProSeries generates the pdf for 2019!