The BookBook for iPhone 12 has had two versions, one of which is MagSafe compatible and one that is not. A BookBook purchased after 30 April 2021 from twelvesouth.com will be MagSafe. If purchased after that date from a retailer other than twelvesouth.com, it's important to ask the retailer which version they are selling.
NOTE: Only the BookBook shell is MagSafe and must be removed from the wallet portion of the case for charging.