By coincidence, the median estimate and world population are both fairly round numbers: 20M deaths on a planet with 8B people. Put another way: 1 in every 400 people on earth died from this disease. It's hard to process.
1 in 400 people are (estimated) excess deaths during the pandemic. This is not the same thing as claiming that all of them were in fact killed by the disease itself.
An incredibly novel infectious disease that kills older people at an intensely meaningful rate is clearly the driver here.
For 2016 that's 1 in 1300 people in the US, a first world nation with world class medical infrastructure.
I wonder what's the worldwide figure? And what % of it overlaps with that 1 in 400?
Even when doctors and hospitals weren't enforcing it, many people were putting off non-critical medical care because they didn't want to go into the hospital or doctor's office and risk getting exposed.
Fewer people being treated, and fewer elective procedures being performed means fewer chances for error.
One exception of course would be ER/ICU staff who were so stressed, overworked, and understaffed that I wouldn't doubt if the number of mistakes in those places increased to some extent.