Shout out to @Barkiologist for the information.
Orange County Register reports that Jordan Tygh, a regional field director for the California Republican Party, posted a photo on social media of “convenient locations” to drop their own ballots.
They are not official drop boxes. The fake boxes are located in Orange, Los Angeles, and Fresno Counties.
The California Secretary of State says that the fake boxes are located at local political party offices, candidate headquarters and churches.