"this image made by OpenAI" is a drm assertion
You wont be able to assert copyright of the picture that you added an OpenAI red bowtie to, thats a DRM issue.
If yes => DRM
If no => not DRM
They make a constructive IP assertion with the watermark claim of origin that persists across mutation. (ie the "artist" signs their work)
They then quitclaim the IP assertion via TOS.
These are not equivalent rights and reversions though and now you have an IP encumbered and weird legal state because of the DRM.
"this image made by OpenAI" is a drm assertion
You wont be able to assert copyright of the picture that you added an OpenAI red bowtie to, thats a DRM issue.