Effects of Google’s December 2020 core update and Recovery from Dec 2020 core update. It has global appeal and its broad core update with a very big and substantial effect on the rankings between December 3rd & 4th.
The December update showed even more changes than the May update in some areas, especially in the top three results. Ranking fluctuation reported by more than 70% of webmasters, gains or declines of 10% to over 100% of their previous levels of organic search traffic. Its impact is bigger than the May core update.
If your site is negatively impacted you can do the changes as we are suggesting in the post Recovery from core update Dec 2020