There may be up to a million more Covid deaths to come, if most of the vaccine resistors chose to get the virus instead of vaccinations. We are already seeing reports that a lot more Republicans are dying than Democrats. Redistricting is going to be based on census data that does not take that into account. So there is a chance that gerrymandered 55% safe districts may not be safe after all. Gerrymandering depends on a static political divide, to group one Party's voters into as many slightly "safe" districts as possible. But if the politics of a district's voters is changing, that district may flip to the other side. Then most of your "safe" districts may shift Party's.
Parties used to try to preserve some "really safe" enclaves, like 60% of the vote or more, just to keep their leaders in the House. It would be really embarrassing if the Speaker of the House lost his seat. (But he or she could still be elected as Speaker!)