Let's start with one assumption: that there is no provision in the corporation's bylaws or other governing documents that requires distributions. If the governing body of the corporation has voted to require annual distributions, then the leadership of the corporation has what is a called a fiduciary duty to comply with that provision.
But if there is no provision in the bylaws or other binding policies, then the answer will most likely depend on figuring out what type of nonprofit this is. People often use the terms "nonprofit," "501(c)(3)," and "charity" interchangeably. But they are different things, and those differences are relevant here. The IRS requires that "private foundations" distribute a certain percentage of its assets annually. The rules for how much needs to be distributed are pretty complex, but for simplicity let's say it's 5%. Under Section 4942 of the Internal Revenue Code, if a private foundation does not distribute the 5% of its assets, there are various penalties that the IRS will impose, ranging from 30% of the amount that was not distributed, up to 100% if the IRS send the nonprofit a notice and the organization still fails to distribute the funds.
So, what is a "private foundation?" Under the Internal Revenue Code, Section 501(c)(3) charities are divided into "public charities," "private foundations," and "private operating foundations." The difference between a public charity and a private foundation depends on how much of the support for the charity comes from the general public (as opposed to insiders and major donors.)
So, the answer to whether a California nonprofit public benefit corporation is required to distribute a percentage of its assets depends on the following: IF the corporation is a "501(c)(3)" charity, and IF it is classified as a "private foundation" by the IRS, and IF none of the fairly complicated exceptions in Section 4249 apply, then yes, the corporation is required to distribute a portion of its assets every year.