iPhone 11 Pro Max Smart Battery Case not fast-charging

Just received it today. I charge my phone with an 87W USB-C Power Adapter from Apple. When I had the iPhone XS Max with the Smart Battery Case, both the phone and case would fast-charge simultaneously. With the iPhone 11 Smart Battery Case, the phone is getting charged first, and then the battery case is getting charged—but while the phone is fast-charging like normal, the battery case is not. Is the case defective?