Apple has made the third public betas of watchOS 7.4 available for download.
Those who wish to participate can download the latest betas and configuration profiles from the Apple Beta Software Program. Subsequent changes for existing participants are available as over-the-air updates on enrolled devices.
When watchOS 7.4 is used in tandem with iOS 14.5 users can unlock their iPhone when wearing a face mask. There aren't any other notable user-facing features for watchOS 7.4 and release notes point to the usual bug fixes.
AppleInsider, and Apple itself, strongly advise users don't install betas on highly-important or primary devices, due to the potential for data loss or other issues. Instead, it is recommended to install betas onto secondary or non-essential devices and to ensure there are sufficient backups of important data beforehand.