I think that depends on the magnitude of the events. It took my parents until about 1960 to finally put the War to rest. Similarly Maggie Thatcher and the Closure of the mines, Blair and Iraq.
I think the long term impacts of the pandemic are only just becoming clear for many people, and they won’t forget.
I also think that even if he hadn’t treated the electorate like fools, many will want to move on, and have a fresh start. I suspect that is also delaying some leadership campaigns - better to let him struggle on for a bit longer through the NI increase, cost of living crisis etc. than to be tainted by association.