A notice was posted by Google saying that, between the dates of June 5 through June 7, it was unable to capture data around image search traffic. This was a bug and it didn’t impact actual search traffic. Even then, the Search Console performance report may show drops in image search traffic in that date range.
The notice read, “June 5-7: 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.”
In order to see this, you can login to Google Search Console, click into your performance report, and then filter by clicking on the “search type” filter. Once you’ve done that, you can then select image from the filters.