There wasn't a special election for the last two months of Feinstein's term a few days ago - that will happen in November, when voters will select both who fills the remaining two months, and who fills the full term:
"We won’t know Butler’s replacement until November
No matter who voters pick to fill behind Butler, they have to vote again in the general election.
The separate ballot questions also mean one candidate could hold the job for two months, and another for the next six years.
And while it’s unusual, that means there will be two general election races on the November ballot – the special election to serve two-months and the regularly scheduled election for a full six-year term."
https://www.usatoday.com/story/news/politics/elections/2024/03/06/california-senate-primary-key-takeaways/72843345007/