MS Paint and Photos inivisibly watermark even locally generated output with GUID

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