iOS 13.4 (build 17E5223h) is an official Apple over-the-air update for the iPhone 6s, released on 2020-02-05T18:17:34Z. The update package is 693.8 MB. This is a delta (partial) update that requires 13.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1d9191148dfd84a8456fffb7834b4ebd1e0c18fb.zip.