Maybe a bug in right side button.

rony-z wrote:

iphone 16 pro max.

when pressing twice the

button on the right side the iPhone goes to “reduce white Point” and the iPhone’s screen becomes dark.

An issue for me.

any advice how to avoid this problem will be appreciated.

https://discussions.apple.com/content/attachment/ad2f8667-9b8b-476f-a379-a5083df5ea96

Make changes and compare your results...

ref: iPhone 16 Pro Max - Apple Support

ref: Learn gestures for iPhone models with Face ID - Apple Support

verify your software is up to date—

The current stable release of iOS including bug fixes, security updates is iOS 26.2

Update your iPhone or iPad - Apple Support

further—

Have you shutdown & restarted the iPhone ie power off/on...if no resolve proceed

Restart your iPhone - Apple Support

Reset or a Force Restart,

Force restart iPhone - Apple Support

Restore from backup, restore as new device.

Restore your iPhone, iPad, or iPod to factory settings using a computer - Apple Support

Put your iPhone in diagnostics mode - identify potential hardware and software issues

How to put your iPhone in diagnostics mode - Apple Support

To be proactive you can file a bug report / submit your Apple Feedback here: Product Feedback - Apple