After restarting the beta process a week ago, and in parallel with the public beta, Apple has an update for the first beta of iOS 17.4 with so-far undisclosed fixes.
Developers taking part in the beta program can acquire the latest builds through the Apple Developer Center or by updating their iPhone via the Settings app. Public beta versions typically appear shortly after the developer versions, and public participants can sign up through the Apple Beta Software Program website.
The new build is number 21E5184k. The previous build was 21E5184i.
At this time, there does not appear to be a corresponding update to iPadOS 17.4.
The changes in iOS 17.4 cover a number of areas, with App Store changes to comply with the EU Digital Markets Act being the chief one. Podcasts gains a new dialogue box icon in the lower-left corner, the Music App replaces Listen Now with Home, an update to Stolen Device Protection, Siri message-reading language support, game streaming app support, and new emoji round out the list.
AppleInsider and Apple strongly suggest users don't install test operating systems or other beta or RC software on "mission-critical" or primary devices, as there is the small chance of issues that could result in the loss of data. Testers should instead use secondary or non-essential hardware and ensure they have sufficient backups of their critical data at all times.