If you've abandoned your domicile in CA and established a new domicile in OR, for 2021 you will file a part-year resident return for each of the two states.
Your income while a CA resident is fully taxable by CA; your income after becoming a resident of OR is fully taxable by OR.
Once your domicile is established in OR, your income is no longer taxable by CA unless you physically work inside CA. CA can only tax a non-resident on CA-source income. W-2 income is "sourced" where the work is actually (physically) performed.
See page 10 of this CA tax booklet for more details on the concept of "domicile":
https://www.ftb.ca.gov/forms/2020/2020-1031-publication.pdf
Thus, if you live in and work exclusively in OR, your employer should cease withholding CA taxes - and ideally should withhold OR taxes for you.
If your employer cannot or will not withhold OR taxes for you, you may want to start making estimated tax payments to OR, to avoid a big tax bill next year. You'll find the details about that here:
https://www.oregon.gov/dor/forms/FormsPubs/publication-or-estimate_101-026_2021.pdf
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
