We are down 50% from the peak of Covid deaths in California. It seems likely we will have one or more days of zero Covid deaths before the end of May. That is the measure I assume they are going for at this point. Source: https://covid19.healthdata.org/united-states-of-america/cali...
The drop you are inferring from your graph appears to be a be a reflection of a noisy data set, and the graph is a week out of date.