If you were a resident of Washington all of 2020, and your only income from California was your retirement income, then that income is not taxable by California.
However, you would have to file a non-resident California tax return, allocating zero income to CA, in order to receive a refund of the withheld CA taxes.
Retirement income is taxable by your state of residence at the time you receive it.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
