On April sixth, Google stated it made an replace to “the algorithm for counting picture impressions in Search outcomes.” This may result in a “Small drop” within the picture impressions you see reported within the Google Search Console Efficiency Report.
Google posted this info on the data anomalies page the place Google wrote, “Search Console improved the algorithm for counting picture impressions in Search outcomes. Consequently, you may even see a small drop in your picture impressions in Search. This isn’t a drop in precise impressions, only a extra correct calculation of picture impressions when kind=picture is specified within the Search Efficiency report.”
So you’ll solely doubtlessly see this begin on April 6, 2021, particular to if you filter your search site visitors by picture search.
Clearly, rankings weren’t impacted by this reporting change.
Discussion board dialogue at Twitter.