All, if you need proof that Feinstein's absence matters, look at today's vote.

https://thehill.com/policy/energy-environment/3973488-senate-votes-to-overturn-biden-truck-pollution-limit/

The vote was 50-49, because:

1. Manchin voted with the GOP,
2. Feinstein is still out.

If Feinstein had been there, it would have been 50-50- and Harris as tie-breaker.

Senate votes to overturn Biden truck pollution limit

The Senate on Wednesday passed a Republican-led effort to undo a Biden administration rule that aims to cut pollution from heavy-duty trucks. The vote was 50-49. Sen Joe Manchin (D-W.Va.) voted with Republicans to get rid of the rule. Sen. Dianne Feinstein (D-Calif.), who has been absent from the Senate amid health issues, did not vote.…

The Hill
@Celeste_pewter As a Californian and constituent, I sent a message to her office regarding this vote and judicial confirmations calling for her to step down if she is unable to perform her senatorial duties. I doubt it makes a difference, but fwiw I guess. Her office's contact info can be found here if anyone else wants to plead into the void:
https://www.feinstein.senate.gov/public/index.cfm/contact
Contact - United States Senator for California