Google announced the November 2021 core update on November 17, 2021: "Later today, we are releasing a broad core update, as we do several times per year. It is called the November 2021 Core Update." The rollout began around 11 am ET with the usual one-to-two-week estimate, per Search Engine Land's coverage, and Google confirmed on November 30 that "The November 2021 Core Update rollout is now complete", a 13-day rollout that Google's ranking updates history still carries.
The timing is what drew comment. Black Friday and Cyber Monday were less than two weeks away, and Google had historically eased off major ranking changes ahead of the holiday shopping season; former Googler Matt Cutts once described the pre-holiday pause as "Google's gift to webmasters". Danny Sullivan acknowledged the criticism and said Google would "take the timing feedback into consideration for future rollouts like this". Data providers told Search Engine Land the update hit fast and hard in its first 24 hours before slowing, with volatility tremors around Thanksgiving and on the final day.
It was the third broad core update of 2021, after June and July, and the standing guidance applies: nothing specific to fix and no penalty to lift. Audit the pages that lost visibility against the self-assessment questions in Google's core updates documentation, improve overall helpfulness, and expect meaningful recovery to register at a later core update. Our recovery guide covers the sequence.