bottomsheet google material library not working on iOS 14

Question

the code that used to work in iOS 13 suddently does not work in iOS 14.

Expected outcome is bottom sheet is shown. However, real result is we just get a giant gray overlay, and nothing is shown on it.

let vc = // some view controller.
let bottomSheet = MDCBottomSheetController(contentViewController: vc)
present(bottomSheet, animated: true, completion: nil)