Your product, ad text, or landing page contains content Microsoft Advertising prohibits. This is a catch-all triggered by automated screens for restricted categories like weapons, drugs, adult, or counterfeit goods.
Product titles or descriptions reference restricted terms; the landing page mentions or sells adjacent prohibited items (e.g., a knife shop also selling tactical weapons); image content flagged by ML classifiers; or prior policy strikes on the merchant account. Microsoft's vague messaging here means root cause requires inspecting the product detail page in MMC.