@SebastianArcq
That is one of the zillion dollar questions!
How many of those people were indifferent? How many had an opinion and wanted to vote, but could not? Of those latter, do we disproportionately prevent from voting people who support one candidate vs the other?
Disenfranchisement is a long-time Republican strategy, and we've recently learned that Russia was running an active demotivation campaign. How effective were those strategies? Did either alter the outcome?