The newest Banned & Restricted announcement only has one card in it: the newly re-released Time Warp. Originally appearing in the Tempest set, the card was republished as part of the Strixhaven Mystical Archive, but it's already proven to be powerful enough that it's being banned from the Historic format.
Time Warp is a critical part of the dominant Jeskai Turns deck, which dominated the Strixhaven Championship tournament: all of the top four Historic decks were Jeskai Turns in this event. Additionally, play data from Historic suggests that Jeskai Turns decks are too dominant, with few bad matchups, and too capable of preventing opponents from being able to properly play the game. The other popular decks from the tournament (notably Izzet Phoenix and Jeskai Control) did not show the same level of dominance, despite making use of Mystical Archive cards such as Brainstorm.
"Though we often like to see how the metagame adjusts to tournament results like these, when the deck involved has play patterns that prevent the opponent from playing the game and when our data suggests that it lacks a significant number of bad matchups, we favor acting quickly," Wizards wrote in their official announcement. "For these reasons, Time Warp is banned in Historic."
The ban will go into effect in Magic: the Gathering Arena on June 10. Stay tuned to Magic Untapped for more news on Banned & Restricted announcements.