The function to_excel of pandas generate an unexpected TypeError

I have same problem with openpyxl=3.0.2,

Refer to this answer, I roll openpyxl back to 3.0.1(conda or pip) and it works.

>>> conda remove openpyxl>>> conda install openpyxl==3.0.1

>>> pip uninstall openpyxl>>> pip install openpyxl==3.0.1

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