To archive the watermark they store every output which they create and let partners check against it. That’s how I understand the article.
Then they also store everything which the partners upload to check if it’s created by them.
If other AI players also would store everything they create and make it available in a similar way there could be indeed some working watermark.
If one would use a private run AI to change the public run AI generated content to alter it there still would be a percentage similarity recognisable to hint that it might come from one of the public AIs.
Timestamps would become quite relevant since much content would start to repeat itself at some point and the answers generated might be similar.
Then they also store everything which the partners upload to check if it’s created by them.
If other AI players also would store everything they create and make it available in a similar way there could be indeed some working watermark.
If one would use a private run AI to change the public run AI generated content to alter it there still would be a percentage similarity recognisable to hint that it might come from one of the public AIs.
Timestamps would become quite relevant since much content would start to repeat itself at some point and the answers generated might be similar.