Google posted on the data anomalies page that due to an internal issue Search Console did not capture some image search statistics from June 5th through June 7th.
Here is the announcement from Google - note, Google did not post anything about this on the social channels, it was just quietly posted on this page:
Google wrote "June 6-7: Some image search statistics were not captured during this period due to an internal issue. Because of this, you may see a drop in your image search statistics during this period. The change did not affect user Search results, only the data reporting."
I personally do not see any significant drops in my specific performance reports within Google Search Console but you can check yours by going into Google Search Console, clicking on the performance report and filtering the traffic search type from web to image:
I reported yesterday afternoon at Search Engine Land and I have not seen any real complaints about this yet. Did you notice any major issues?
Let's not forget the data loss from April 9 to April 25th but that was a much bigger issue.
Keep in mind, there was no impact to rankings, this is just a reporting issue.
Forum discussion at Twitter.
Update: Glenn sees a drop in data, I still don't across many properties:
Google Search Console Missing Some Image Search Traffic Between June 5th & 7th.
— Glenn Gabe (@glenngabe) June 18, 2019
See the screenshot below for an example. Not all image search traffic dropped, but def. some: https://t.co/CuM8vquYcN via @rustybrick pic.twitter.com/MALOkhVYz6
