iPhone X suddenly lagging on CODM

Hi itsAtrix,

For help with iPhone performance, view the information below found in the article here: If your iPhone or iPad gets too hot or too cold - Apple Support

"If your device gets too warm

iOS and iPadOS devices have built-in protections to prevent overheating. If the interior temperature of your device exceeds the normal operating range, your device will protect its internal components by attempting to regulate its temperature. 

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 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."

Based on the information provided you're operating your iPhone in two of the conditions where performance can slow if the internal temperature is exceeded. As recommended in the same article "To resume use of your device as quickly as possible, turn it off, move it to a cooler environment (away from direct sunlight), and allow it to cool down."

You can also find helpful information about battery life and performance here: If your iPhone or iPad is running slow, and here iPhone Battery and Performance

If you have further concerns, reach out to Apple Support directly to assist.

Contact - Official Apple Support

Contact Apple for support and service - Apple Support

Best.