I am not aware that there are any bundles created by Itch. Was that a thing they did in the past? Can you link to a current bundle? There is winter sale. If such bundles still exist, there should be one right now.
Actually I am not aware of any promotions Itch does, at all, beside the featured and fresh lists on the homepage. And maybe "picks" of bundles. I misread. Those are just featured lists of sales, not lists of bundles. Anyway. Even with coop bundles, there is always "A bundle hosted by" and that by is not Itch, but a developer.