It looks what usually happens during times of turmoil: People vote against those who are currently in control.
Trump lost because he was the guy in power .
The Democrats lost a lot of seats (particularly on the state level) becuase they were the ones in control there.
Midterm elections the Democrats are going to lose more seats. Don’t blame Biden. (I’m sure the pundits will) The party in the White House has almost seats during for the past hundred years. this time it will be worse because the US will still be dealing with the aftereffects of the Corona lockdowns