He's always been tetchy. It's terrible and very unappealing trait. Sunak was like that too - perhaps even more so. Gordon Brown, ditto.
I watched the Blair interview with Amol Rajan last night and my wife and I commented on it. I am no fan of Tony Blair but he was always calm and measured in his reponses and never came across as a petulent brat. Ditto John Major. Always calm, always measured, always dealing with the question with decorum.
Starmer could do well to learn this, altough I don't think he has it in him. Too many years of lecturing others in the courtroom I suspect, dishing out the awkward questions, not taking them.