I don't think Covid had a thing to do with it. Trump was disliked, especially by independents from the get go. Go back to 2016, independents did vote for Trump, 46-42 over Hillary, 12% voted third party against both Trump and Hillary. Add Hillary's 42% with the 12% who voted against both candidates because of their dislike of both, you have 54% voting against Trump. Independents gave Trump a 40% favorable/57% unfavorable Nov 2016
Fast forward to 2018, because of independents dislike of Trump, they voted for Democratic congressional candidates 54-42. Nov 2018 enabling the democrats to gain 44 house seats and take control of the House. Independents viewed Trump in Nov 2018 40% favorable/58% unfavorable.
In 2020, independents voted for Biden 54-41, independents view of Trump Nov 2020 was 39% favorable/60% unfavorable. What is the favorable/unfavorable ratings important? History shows folks usually don't vote for someone they dislike. Independents are very important to the Republican Party. Since the GOP is the smaller of the two major parties in party affiliation/identification, the Republican Party needs to win the independent vote or lose the election.
Finally you need to look at the total percentages of 2020. Trump 46.9%, Republican congressional candidates 48.1%, Republican senate candidates, 49.3%, Republican governors 52.4%. On the reverse side, Biden received 51.3%, Democratic congressional candidates 50.4%, Democratic senate candidates 47.0%, Democratic governors 44.1%. Down ballot republicans out performed Trump, down ballot democrats failed to match Biden's vote total and percentage.
Trump was low man on the totem poll among Republicans vote getters percentage wise. Congressional Republicans did better than Trump, Republican senate candidates did better than Trump, Republican governorship candidates did a whole lot better than Trump. You could carry this on to state legislatures also.
There was a whole lot of ticket splitters who voted for Biden against Trump, then voted Republican down ballot. This should tell those who belong to the GOP something. But they totally ignore it.