Xiaomi
Turn On/Off Proximity Sensor During Calls auf Xiaomi
The proximity sensor sits near the earpiece and detects when the phone is close to your face. During a call, it tells the display to turn off so your cheek does not trigger touch actions like muting the call or switching apps.
If this setting is disabled, the screen stays fully lit and responsive throughout the call. That is when accidental taps happen most often, especially switching on speakerphone or ending the call without meaning to.
On MIUI, this option lives inside the call settings rather than the general display menu. Open Open the Phone app ➔ Open the Settings ➔ Tap on Incoming call settings ➔ Enable or disable Proximity sensor.
Turning it on darkens the screen as soon as the phone gets close to your ear and lights it back up when you pull the phone away. Turning it off keeps the display active the whole time, which some people prefer if they use a case that already covers the sensor or if the sensor misreads distance and blacks out the screen too early.
If the screen still does not respond correctly after enabling the sensor, a dirty sensor cover or a thick screen protector near the earpiece is often the cause rather than a software setting.