libQt5Core.so.5: version `Qt_5.15' not found

In Xubuntu 21.04, it comes standard with Qt 5.15.2 components.  I have made no changes to any Qt component or other GUI component except to keep my system up-to-date.

I just installed from apt the qttools5-dev-tools (version 5.15.2-5 Qt 5 development tools) which includes the Qt Designer.  I ran the designer and

• generated the simple dialogue ui
• saved the Python code
• executed the Python code

Result:

ImportError: /home/elkins/.local/lib/python3.9/site-packages/PyQt5/Qt/lib/libQt5Core.so.5: version `Qt_5.15' not found (required by /usr/local/lib/python3.9/dist-packages/PySide2/QtCore.abi3.so)

This ("`Qt_5.15' not found") is a bit perplexing because (a) all of the installed Qt components are version 5.15.2 and (b) the name of the file that was sought is not displayed as-is.

LD_LIBRARY_FILE is nil.  The libraries found are in the /etc/ld.so.cache.  The source for the cache is attached (.conf files).  Also attached is a screenshot (xx.png) showing my use of Qt Designer.

If I need to provide any other information or execute any commands, please let me know.