Thanks for reporting Prototype issue, it looks more like a bug than security vulnerability.
As per the description and my understanding, if proto, __proto__, toString, etc strings are used as filenames, then it has the potential to corrupt the zip file.
As per the preliminary testing done with this example:
https://paramquery.com/pro/demos/export_group_columns, passing the supposedly problematic filenames results in no problem or error whatsoever and the downloaded zip / xlsx files open without issues.
So apparently it doesn't have any impact on pqgrid use of jszip 2.5.0, unless you find or come across some issue with reproducible steps.