Do AI-generated images actually contain hidden metadata (like prompts, model used, etc.)?

Hey! I was looking into how people distinguish AI-generated images from real photos.
I know regular images usually have EXIF data like camera model, focal length, shutter speed, etc.

But I also read that AI images can contain their own type of metadata, things like the prompt used, the model name, sampler, CFG, steps, etc.

My questions:
• Is this true for all AI tools or only some?
• Do platforms like Instagram/WhatsApp remove that metadata just like EXIF?
• How reliable is it to use metadata to confirm if something is AI?
• And if someone wants to hide the fact an image is AI, is it easy to strip that info out?

Trying to understand what’s actually stored inside AI images vs normal photos. Thanks!