That was a wtf to me, so I checked Apple’s latest iOS release security content and GLM & z.ai is mentioned once (under WebKit), Anthropic is mentioned twice, Codex is mentioned once. Not clear if there are other instances where the model did most of the work but wasn’t credited. I didn’t bother to check other releases.
It’s very likely they found all of them, but that the same happened that happened to Microsoft a couple of decades ago: NSA orders not to disclose / fix them so that they can put it in their collection of unfixed zero days.
I'm not a gambling person, but if I was this would be my bet.