python xml won't parse

Question

Trying to read bulk data from US Patent and Trade Office. Have tried several xml files from here, I get the same results:

import xml.etree.ElementTree as ET
import re
file = 'ipgb20210105.xml'
tree = ET.parse(file)

yields: "ParseError: junk after document element: line 862, column 0"

Have tried recommendation to wrap with fake root node, but this doesn't work either:

with open(file) as f:
    xml = f.read()
tree = ET.fromstring(re.sub(r"(<\?xml[^>]+\?>)", r"\1<root>", xml) + "</root>")

yields: "ParseError: not well-formed (invalid token): line 2, column 2"

Any help much appreciated!