It’s a button for the AI assistant – “second memory”
Unless I can be convinced that AI is entirely private & secure I’m not using it. This means I would be paying for a button that is redundant. Hopefully other useful actions can be mapped to this button, such as:
Press to momentarily switch off ‘Sensors Off’ (to adjust screen brightness).
Long-press to momentarily switch off ‘Sensors Off’, open Camera app, and enable camera & microphone access (access off by default).