iOS 15.4's first beta is the one that finally added Face ID with a Mask feature, as well as improved 120Hz support on iPhones 13 Pro. Now, Apple has released 3 further betas in a process that has culminated in the appearance of features that might render some users more content while using their mobile devices.
The company is up to iOS 15.4 beta 4 at this point, which means users on this update channel should see an updated Find My app, which offers more granular Find My and Tracking controls intended to address the recent AirTag abuse controversy.
On that note, iOS has been able to inform the user of the accessories detected around them; now, the 15.4 betas have conferred the ability to specify what they are (AirTags as opposed to AirPods, for example). The developer previews also now include a disclaimer intended to discourage malicious AirTag use by emphasizing that the smart-tags are linked to one's Apple ID on activation.
Tap to Pay on iPhone has also been detected on iOS 15.4 beta 2 - which also reportedly brought up an interesting notification inviting users to opt in or out of submitting audio recordings made by their iPhones (for services including Siri) to Apple for its analytics.
This would have been strange, as users should have been able to set these preferences back as far as iOS 13.2. However, it seems iOS 15.2 revoked Improve Siri & Dictation controls "for a small portion of devices", as Apple conceded when the issue came to light.
In other words, audio recordings from a certain proportion of users may have been sent to Apple without their knowledge or, possibly, their consent. However, it seems this most recent example of consumer privacy disregard on the Cupertino giant's part should be addressed with the general release of iOS 15.4.