I am not sure what level of compatibility koji promises between client and server (likely that should be documented) and they might also be able to see some way to make this work for you (but I shouldn't speak for them).
Do you have any duplicate package there? or only one python3-pyqt5-sip? Does 'rpm -V python3-pyqt5-sip' show anything?
Is /usr/lib64/python3.7/site-packages/PyQt5/sip.so correct for the package?
Do you have another sip.so somewhere?