Under Philippine law, your PH passport was voided when you took your US oath. You may go through the PH citizenship re-acquisition process, then apply for a new PH passport. From https://newyorkpcg.org/pcgny/faqs/#dual-citizen-faq --
I still have a valid Philippine passport, which I renewed before I got naturalized as a US citizen. Now that I have retained/reacquired my Philippine citizenship, can I still use this passport?
No, your old Philippine passport was rendered null and void the moment you were naturalized as a US citizen. You must surrender it to the Consulate for cancellation. You are, however, eligible to apply for a new Philippine passport upon the successful retention/reacquisition of your Philippine citizenship.
The Philippines allows dual citizenship, but it is not automatic. A Filipino loses their PH citizenship the moment they take the US oath, rendering their old PH passport invalid. They will need to go through the citizenship re-acquisition process and apply for a new passport.