My iPhone 12 promax screen dims

Hello Easy108,

It seems that behavior is expected if your iPhone's interior temperature of your device exceeds the normal operating range. You can view more information in the bullet points below found in the article here: If your iPhone or iPad gets too hot or too cold

"If the interior temperature of your device exceeds the normal operating range, you might notice these changes:

• Charging, including wireless charging, slows or stops.
• The display dims or goes black.
• Cellular radios enter a low-power state. The signal might weaken during this time.
• The camera flash is temporarily disabled.
• Performance slows with graphics-intensive or augmented-reality apps or features."

Also found in the same guide these things can happen when:

"Avoid these conditions and activities because they might change the performance of your device:

• Leaving your device in a car on a hot day.
• Leaving your device in direct sunlight for an extended period of time.
• Using certain features in hot conditions or direct sunlight for an extended period of time, such as GPS tracking or navigation in a car, playing a graphics-intensive game, or using augmented-reality apps."

If you have additional concerns reach out to Apple Support directly using the link here: Get Support

Best.