Here's the problem in a nutshell:
1. Kamala Harris resigned from her senate seat to become vice president after the 2020 elections.
2. California Governor Gavin Newsom chose Alex Padilla, who is neither Black nor Asian nor female (unlike Harris) to replace her. To quell the uproar over that pick, Newsom pledged to nominate a black female to the Senate in the event he was faced with an opening.
3. Given that Feinstein was obviously not going to be able to run in 2024, several prominent Democrats have announced their intention to run. Only one of those is a Black female, Barbara Lee.
4. If Newsom lives up to his promise he will have to pick a Black woman. And he pretty much can't escape that if he wants to have a chance to run for president.
5. Some rising white stars in the party like Katie Porter and Adam Schiff have also announced their candidacy, and would hate to find themselves up against the only Black woman in the Senate.