Daniel Hillier added the comment:
This looks to be expected behaviour for the zip64 extension in the zip spec
(for handling large files or large archives).
Section 4.4.1.4 of the zip spec outlines when the zip64 extra fields are used
(https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.T
New submission from Bram Stolk :
This has been tested with Windows Python 2.7 and Python 3.8
If you get the ZipInfo objects of a ZIP file that is larger than 2GiB, then all
the ZipInfo entries with a header offset > 2G will report phantom 'extra' data.
import zipfile
zipname = "reallybig.zip"
