"Confirmed cases" is not a good measure
Because it doesn't reflect how many infected people there are
It just reflects how many you've tested.
As you know, UK had a very bad record of insufficient tests, and is now attempting to catch up.
"Excess deaths" is a fairly good idicator of how many people the pandemic has killed.
For example, the number of "confirmed cases" on the day the Cheltenham festival started, was lower than the number of recorded deaths two weeks later. But we know that those who died were already infected, we just hadn't recorded them. Nor the number, probably twenty to a hundred times more, who had been infected and hadn't died.
BTW, do you know why Germany and Italy and France aren't on your picture?