iOS 13.3.1 (build 17D5050a) is an official Apple over-the-air update for the iPhone 11 Pro Max, released on 2020-01-22T18:07:27Z. The update package is 253.66 MB. This is a delta (partial) update that requires 13.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 475e71148e6c82bc6c8845ad2ac3263789089ee3.zip.