I always go back to “clear and obvious error”, he wasn’t “clearly” offside it wasn’t an “obvious error” decision of penalty should have stood but will all know VAR is a bag-o-shit. Linesmen (or women) not giving obvious offsides and allowing play to continue is another fucking nonsense that’s going to result in needless injuries.
Back to the OP, too much variability in interpreting the rules by individual refs. That’s the problem to me, no one was thinking penalty last night except the ref. Is he pointing to the spot? He’s given a penalty. They retrospectively then say ah yeah that was a penalty. Fucking bonkers.