California local and state officials have not maintained voting rolls by consistently removing who have died or have moved out of precinct, city, or state.
HOWEVER, that is true of all or almost all 50 US states, and on a similarly large scale. California is far from unique in this respect, and may not even be the worst offender among the states of the US.
This is one of the dangers of universal mail-in voting. Ballots are sent to every person on the rolls. Some people will get multiple ballots from the several places they've been registered. Other ballots will go to old addresses and the present resident thereby receives multiple ballots. Multiple ballots to individual persons is an engraved invitation for fraud. Just picture the fraud potential in ballots being sent to nursing homes for large numbers of now deceased former residents ...