Google announced the December 2024 spam update on December 19 and marked it complete on the Search Status Dashboard on December 26, 2024, after 7 days and 2 hours. It was the third and final spam update of 2024, following the March and June spam updates, and it began just one day after the December 2024 core update finished, an unusually dense end to the year that pushed ranking changes into the holiday week.
This was a general spam update: it improved Google's automated systems that detect violations of its spam policies across the board. Search Engine Land reported it was not a link spam update and did not automate the site reputation abuse policy, which Google was still enforcing only through manual actions at the time. The same coverage noted the update hit hard within a few days and appeared more widespread than some previous spam updates.
If your site dropped in the December 19-26 window, review Google's spam policies and remove anything that violates them. Spam updates are algorithmic, so no manual action appears in Search Console and there is nothing to file a reconsideration request for; improvements register as Google's systems recrawl and reassess the site, which can take months.