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Google has documented that it lost or "dropped" data around image search clicks. Google wrote "Some image click data was dropped; as a result, you might see a dip in both click rate and CTR during this period. The issue has been fixed. This happened between the dates of Thursday, November 14th and Tuesday, November 19th.
Google said this is only a "Search Console reporting" issue and does not impact "your performance on Google Search."
Google Search Console has lost data before, so this is not that uncommon.
Just note that when you are filtering your Google Search Console performance reports by image traffic, you may see a dip in clicks between those dates. It is not a reflection of any change in image search but rather just a reporting bug.
Forum discussion at Twitter.
