Static noise
Why is my phone making this static noise while playing music iPhone 12 Pro Max happens on and off
iPhone 12 Pro Max, iOS 14
Question marked as
Top-ranking reply
Slight chance you may have a hardware problem
First try a forced restart
https://support.apple.com/guide/iphone/force-restart-iphone-iph8903c3ee6/ios
If that does not help the next procedure would be to backup then restore your device to factory, and setup the device without restoring a backup, to see if the issue is replicated.
Then restore the backup.
If you need to send the phone in for repair then backing up and restoring to factory would be needed anyway.
Here is a guide for those steps
Backup and restore
(1)How to back up your iPhone, iPad, and iPod touch – Apple Support
Remove SIM PIN if you have set one
(2) Restore your iPhone, iPad, or iPod to factory settings – Apple Support
Set up as new from the Hello Screen without restoring backup. Test if the problem still exists
If not then restore the backup.
If the problem remains then arrange a repair including details of these tests.
https://support.apple.com/en-gb/iphone/repair/service
(3) When your phone comes back Restore your iPhone, iPad, or iPod touch from a backup