iPadOS 12.4 (build 16G5077a) is an official Apple over-the-air update for the iPad mini 3 (China), released on 2019-07-16T17:39:01Z. The update package is 279.66 MB. This is a delta (partial) update that requires 12.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8c8234494c04b8c08f9b83895d2579830a354f97.zip.