Google has announced a new Pixel Feature Drop that also contains the December 2021 security patch. All recent Pixel smartphones are eligible, starting with the Pixel 3a and Pixel 3a XL. However, Google is not ready to push its new Pixel Feature Drop to Pixel 6 or Pixel 6 Pro.
https://www.notebookcheck.net/Google-releases-Pixel-Feature-Drop-with-December-2021-security-patch-for-the-Pixel-3a-to-the-Pixel-6-and-Pixel-6-Pro.583289.0.html