For Bing PLA, the "Bingbot" crawling our images forces Connexity to download and process each offer image for a merchant. The Connexity image resizer pulls the image from the merchant, resizes the offer image, and caches it. Your PLA's are being rejected or flagged because Bingbot can not index these images fast enough.
Bingbot crawls images and product landing pages, constantly harvesting offer images from the Connexity image resizer. To ensure the operational quality-of-service for our image resizer, we set a 200rps rate limit for Bingbot. It does not block Bingbot, however, it may take additional time for it to crawl images until it will be able to unflag your campaign.
In our new Publisher Exports, we developed the PLA feeds to provide the original merchant image URL, which eliminates the need for Bingbot to crawl Connexity for resized images. Connexity recommends publishers to use the new PLA feeds instead to prevent PLA rejections or flagging from Bing's end.