IPhone 12 mini screen flickers when turning mobile data on.

Hi bharathy30,

For help with unusual issues, test a normal restart of your iPhone with the steps below, found in the article here: Restart your iPhone - Apple Support

"How to restart your iPhone X, 11, 12, 13, or later

1. Press and hold either volume button and the side button until the power-off slider appears.
2. 
3. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
4. To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo."

If the issue continues, ensure you have a backup of your iPhone and install the latest iOS available with the steps here: Update your iPhone or iPad

Reach out to Apple Support directly if the issues remain.

Contact - Official Apple Support

Contact Apple for support and service

Best.