You don't seem to understand how natural selection works. The people whose lives have been extended from 70 to 80 years are well past their reproductive years,

You don't seem to understand how natural selection works. The people whose lives have been extended from 70 to 80 years are well past their reproductive years, so their genes have already been passed on (or not) and their early death due to COVID-19 can't change that. So when the pandemic kills people in that age group it is not affecting natural selection.