When will Core Web Vitals become a ranking factor?

We can answer this question since November 2020. Core Web Vitals will become a ranking factor mid-June 2021. As of mid-June, Core Web Vitals will be roled out gradually.

Together with this ranking update, a visual indicator will be added to the SERP's as well. Do note that they will be testing a visual indicator prior to Core Web Vitals becoming a ranking factor. See my November article on Core Web Vitals highlighting per May 2021.