Source: Google
Google has temporarily disabled the useful Hold for Me feature on Pixel 6 phones that received the December update. A bug in this release is causing trouble for these devices. But it only affects those Pixel 6 phones that have updated to the December security update. Some might also lose the Call Screening option.
Hold for Me allows Google's Duplex technology AI to hold the line for you while waiting for an actual person to come on the line. It's useful when you're trying to get in touch with businesses. Call Screening prevents robocallers from reaching you on your device.
Source: Engadget