The bills have to originate in the Assembly, but they have to pass both chambers to become law.
Both chambers has a 2/3rds majority, and we have MoonBeam as Gov.
Also, the Democrats still don't have two-thirds of the Senate even when you account for the vacant seat, because 2/3rds of 39 is 26. 25 is less than 26 and the lieutenant governor only has a vote in event of a tie.
Newsome can vote in the case of a stalemate. So IF the Republicans ever attempted to filibuster or there were a tax vote, then Newsome can and does cast a vote.
That's not true. The Democrats have 25 seats in the California Senate, but require 26 for a 2/3rds majority and the lieutenant governor only has a vote in case of tie, not just whenever he feels like it.