12-bit colour depth photo

iPhone 12 Pro and iPhone 13 Pro can capture 12-bit photo when ProRaw turned on. But iPhone 14 Pro and iPhone 15 Pro can capture only 10-bit when ProRaw turned on. Why ? It seems to be a huge downgrade in terms of Total Colour information in a Photo. A 10-bit Colour depth photo contains 1.07 Billion colours. On the other hand a 12-bit Colour depth photo contains 68 Billion colours.

Please answer my question. Help me if there is any way to capture 12-bit photo on iPhone 15 Pro Max whether it is ProRaw or even heif or even jpeg.