This year it is a trend for device manufacturers to launch new flagship devices without new operating systems or new features/functions. For example, the Pixel 9 was launched with Android 14 instead of Android 15. Then the iPhone 16 was launched with iOS 18 without Apple Intelligence. Recently, new information has been discovered that may be a factor in why the stable version of Android 15 is slow to arrive on supported Android devices.
Google seems to be mandating Android 15 devices to support Ultra HDR displays. Then, the default camera application must use the JPEG_R image format. What are Ultra HDR and JPEG_R? It is a dynamic HDR display on the device's screen, where parts of the image exposed to light are brighter than others. Then the JPEG_R file stores the HDR data which is the Recovery map to be detected by applications such as albums or Google Photos.
This is only mandatory if manufacturers want their Android 15 devices to be recognized by Google. If just using AOSP Android 15 for custom ROM or development version devices – Ultra HDR is not required. Ultra HDR support also varies by device such as Samsung with Super HDR, Nothing with Ultra XDR or Oppo/OnePlus with ProXDR.