Seems this is not handling base64 image properly. Maybe something like this can fix it.
from io import BytesIO
from docx import Document
# Your base64 image string
base64_img = 'your_base64_string_here'
# Decode the base64 string to binary
img_data = base64.b64decode(base64_img)
# Use an in-memory bytes buffer
img_stream = BytesIO(img_data)
# Create or open a document
doc = Document()
# Add the image to the document using the in-memory stream
doc.add_picture(img_stream)
# Save the document
doc.save('your_document.docx')
https://github.com/pqzx/html2docx/blob/9337c3950bee62a4fea5b722e7ba19c163df4d9f/htmldocx/h2d.py#L312C30-L312C41
Seems this is not handling base64 image properly. Maybe something like this can fix it.