The Doku situation was a borderline call that required some judgment, to call it transparently 'correct' does not reflect the reality of the situation. There is contact but he pulls back a bit at the end, and Mac Allister closes his eyes and starts falling before the contact is made. Furthermore, the penalty box is filled with players behind the ball, making it a lot harder to argue that a goal-scoring opportunity has been denied – that, after all, is the pretext for handing out the enormous reward of a penalty kick, with 85% chance of scoring.
Even the Ederson foul on Nunez was a judgment call – it was pretty easy to see that there was zero contact on the play, but you can judge that Nunez would have been kicked if he hadn't tumbled over like an acrobat, and given that he reached the ball first would have had a dangerous run towards goal if not for Ederson's intervention. Therefore, a penalty.
The thrill of today's match was the intensity – you could see both sides struggling with the weight of the occasion. Diaz for instance couldn't find the composure because he felt how big the moment was. The title race, the great rivalry that has developed, Klopp's last match against Guardiola, the Anfield atmosphere – that is what matters in football. To award a penalty at the last minute for a minor and contextually insignificant infraction because of the 'letter of the law' and the forensic evidence of contact from Doku's boot would have made the game about the Law, the Bureaucracy, the Rules, and it would have been a great shame. Credit to Oliver & VAR for letting it go.
Also, the hold on Trossard yesterday wasn't a penalty, he wasn't going to get to or do anything with that ball. It did not affect the game, move on. We absolutely lost focus in the second half yesterday because of moaning about calls, and we're fortunate we didn't get punished. And the idea that Gabriel or Arsenal is unfairly targeted, come on – you can read every PL fanbase on twitter and message boards insist that there's a devious conspiracy against their club. It's ridiculous.