I don't think that the vast majority do not care about PMQ's. Labour have closed a 20 point gap in just 3 months and that is, in part, due to Starmer taking Johnson apart at PMQ's. Once you reach a tipping point, even people with no interest in politics will jump on a bandwagon as they will assume Starmer is the better option as he is more popular.
I would think that the covid crisis has caused part if the swing, but it is the forensic examination of Johnson at PMQ's that reveals Johnson and his cabinet for what they are, talent-less.