The only real example of youth-focused voter suppression given in that article is the removal from electoral rolls of those who have moved home, and are then registered in two states (which disproportionately affects the young due to the higher incidence of moving home).Going to echo Sean here in saying that it's difficult to tell if youth turnout was low because it usually is or because there was active voter suppression methods instituted by both parties that disproportionately effect demographics that tend to vote more progressive.
Stop Blaming Young Voters for Not Turning Out for Sanders
Sanders is losing to Biden because America is excluding young voters, persistently and systemically.www.theatlantic.com
It also talks about the lack of easier registration methods (or auto-registration). This suppresses the vote, and automatic registration should be implemented, yes. But surely it only has an outsized impact on younger voters because of the lack of prior engagement. The lack of engagement must come first, here, in order for it to have an impact at all.
Then we come to the lack of dedicated civics lessons and lack of online engagement. Extremely good ideas, though lacking them isn't really voter suppression, and they also seem to actually bolster the argument that Sanders would have had a very tough time building an electoral coalition around the young.