Did you RTFA?
It would be helpful if he included actual numbers in the article instead of just posting links to external sources that may be unreliable or subject to change.
The Pennsylvania SURE report for 2020 indicates that 6.945 million votes were cast. I believe the final official results for the presidential election had 6.915 million total votes for the three candidates on the ballot in PA (Trump, Biden and the Libertarian Party candidate).
Where does this guy come up with 90,000 or 121,000 “extra” votes?