The common card Cranial Ram has been banned hours before it would hit the tabletop. Apparently, this card would be simply too much for Pauper decks because it is a Living Weapon card that increases power based on the number of artifacts in play that can be reequipped to other creatures once the Germ token it is attached to dies. This card would've been unbalancing in Pauper because of all the cheap artifacts and artifact lands floating around the format. WotC designers had banned All That Glitters recently from Pauper for similar reasons (see "Banned and Restricted Announcements").
Modern Horizon 3 prereleases start today, June 7, 2024, and the official release of the set is next week (see "Modern Horizons 3'").