Microsoft Paint and Photos Embed Server-Issued GUIDs as Invisible Watermarks in Locally-Generated Images

TL;DR Microsoft Paint supports both local and cloud image generation Paint and Photos also ship local AI models The two apps send the prompt to a remote server for moderation The server returns a GUID along with the moderated prompt The GUID is embedded into the locally generated image as an invisible watermark A separate visible-watermark setting does not control this invisible watermark On Copilot+ PCs, image generation is local but prompt moderation remains remote Microsoft discloses that Paint adds C2PA metadata to AI-generated images AI-generated image saves limited to C2PA-preserving formats: PNG, JPEG, GIF, and .paint