Google Merchant feed warnings from one image CDN setting

I saw a batch of Google Merchant Center warnings that pointed to product images, but the images opened fine in a browser. The feed had correct URLs, the CDN was online, and the product pages looked normal. The warning said image fetch failed, which made it tempting to resubmit and wait. I checked the raw feed, image headers, CDN rules, and Google's fetch timing. The issue was a hotlink…