iOS 13.4 (build 17E5223h) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2020-02-05T18:17:25Z. The update package is 801.7 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: 8715bcb7519dc3e7d2de97e77578f520b1e26962.zip.