From Cal Matters:

Voters are first asked whether they would like to give the incumbent the boot. Then, in a second question, they are asked who ought to be the replacement. Under California law, incumbents can’t run to replace themselves.

If more than 50% of voters opt for a “yes” on the recall question, whoever comes first on the replacement list is immediately hired as the state’s next chief executive. That’s where things can get weird. In a crowded field with no clear frontrunner, coming first could mean getting far less than 50% of the vote. 

It might even mean getting far less support than the incumbent being ousted. …

A more recent example shows just how odd California recall math can be.

In 2016, Democratic state Sen. Josh Newman won a seat in a longtime GOP stronghold in north Orange County. In the summer of 2018, Republicans and anti-tax advocates mounted a recall campaign over Newman’s support for an increase in the state gas tax. A fired-up conservative bloc of voters turned out en masse, Democratic voters did not, and Newman was replaced by Republican Ling Ling Chang. 

In that race, 66,197 voters, or 42%, opposed the recall and backed Newman. Chang, running against five other candidates, received fewer votes, 50,215, but still won the seat with 34%. In the next regularly scheduled election in 2020, Newman reclaimed the seat. 

A sufficiently crowded and disorganized field could produce similar results in a 2021 recall race.