The Democrats will likely lose seats in the House and Senate (as is expected for the party in the White House). Maybe they can keep their losses to a minimum, but 2022 is going to be an especially challenging cycle because of redistricting.
A lot of the house seats that flipped in 2018 aren't going back anytime soon. Maybe some of the unexpected ones like the Oklahoma, SC, NM, UT, upstate NY seats (which might switch back in 2020 anyways). But the Philly, DC, OC burbs aren't flipping back because a moderate democrat was elected President in 2020.
I actually think that the GOP path to the House will be built on some of their "close call" seats in 2016 (ones that trended rightward but not enough to win), not these suburban seats that they won in 2018 - such as CT-05, OR-04, OH-13, and MI-05 (or whatever the equivalent seats will be post-redistricting). Basically, it would be the Republican equivalent of the Democrats winning VA-07 or IL-14 in 2018.