Crash when re-implementing createMimeDataFromSelection on QPlainTextEdit

I've been trying to strip out the mime styling information from the QPlainTextEdit on copy. To do this I've tried re-implementing createMimeDataFromSelection. Creating a new QMimeData object and returning that from createMimeDataFromSelection results in a crash in PySide2. But not in PyQt5.
 
I've attached a python file illustrating the issue. If I try to copy out of the 3rd QPlainTextEdit it crashes. If the PySide2 import is changed to PyQt5 it works as expected and does not crash.
 
I initially created a stackoverflow post about this issue before realizing it works in PyQt5 as expected. There is some more info there about what I was trying to accomplish.