The red was crystal clear, the issue is that Gordon touches Dijk on his shin guard - and removes the stocking (I hope that's the correct word).
It was unintentional and clumsy, but even Gordon apologized for a 'reckless' tackle - so everybody can see it was a good call.

Added on time was fair as well - there were many interruptions with both Tonali and Schar needing lengthly onfield interventions.

That all being said - Liverpool was lucky. And it was the 2nd time in a row this season. Newcastle were brilliant with 10 players and showed to the whole league that physicality will disrupt Liverpool's flow.
I expect more teams to follow this example - and Liverpool to struggle against it.

Oh yeah, Kerkez is a dumbass as well.