Should uploaded but not yet reviewed AI generated content be removed to comply with the new rules?

Why? The rules did not change a lot. You can now submit in a different category, and you do not need a property release any more. I suppose it's in your interest to keep the assets in the queue.

It seems quite unlikely that Adobe intended for Generative AI Contributors to delete all of their pending submissions and re-upload them, and they have not stated this as a requirement. Certainly, there must be millions of Generative AI assets waiting for review, with some Contributors having hundreds queued up. Nevertheless, these recent changes to the upload process are going to encourage an even faster rate of submissions, so it's possible that the queue will get even longer.