Its a bit below par yes. More things to take into account though: if you are leading a game you statistically have close to a 90% chance of scoring from a penalty, while if you're trailing you have about a 60% chance of scoring - all psychology.
Indeed it was all kinds of offside. Would have been ruled out. Tbf very unusual situation and I don't think many in the heat of the moment thought of it as offside since it is so deeply ingrained that the goalie is in... the goal.
Bernardo Silva is also quite good at "Football". And football.
Sticking his left foot like that is indeed a clever, dirty trick, but the main reason there was a penalty was because Lewis Dunk fouled the opponent.
Bernardo was going forward, Lewis Dunk tried to get the ball and upon realising...