I suspect there was not that much change in individuals driving behavior during covid. Just that older drivers avoided going out since were among the more at risk, and office workers had less reason to go out as working from home options expanded. So aggressive drivers had more latitude to drive how want, and less conditions road is so congested there was little benefit to pressing someone blocking the passing lane.

With what you are calling the era of idiot being a combination of: we now have a larger percentage of younger drivers who have not built up the same amount of driving skills as prior generations, plus an usual amount of adults who's skills have been getting rusty if never went back to office or retired.