Five-term California Rep. Alan Lowenthal just became the 20th Democrat to announce his retirement, so he won’t be running for reelection in 2022.
As noted at the link, he’s 80 years old, so this might only be partly due to poll news like this: Rasmussen reports that in the generic Congressional preference poll, voters now prefer Republicans over Democrats by 48-39%. Usually, just a tie suggests a big GOP win.
The story also notes another problem the Democrats are facing, and that’s the age of their incumbents. In California, there are nine Democratic Congressional incumbents who will be over 75 by Election Day, and another 11 who will be 65+. Or as Nancy Pelosi calls them, “the junior members.”