Apple released iOS 14.2.1 to the public today, with notable bug fixes for MMS messages, hearing devices, and the responsiveness of the touchscreen on the lock screen on the iPhone 12 mini.
A user of the Apple support forums described like this your problem:
My phone’s screen randomly stops registering touch input only when inside a case and also with a screen protector turned on. With just the case on, the screen is fine, and just with the screen protector on the screen it works fine. Only when combined does my screen go crazy.
iOS 14.2.1 improves the iPhone 12 mini experience
With the latest update, Apple aims to fix some lingering problems for users who own an iPhone. The main solution is for the iPhone 12 mini, with software intended to fix a bug that could make the lock screen unresponsive. With this software update installed, the issue is fixed for iPhone 12 mini owners.
Additionally, iOS 14.2.1 also fixes an issue where some MMS messages may not have been received. The new version addresses several notable issues where iPhone 12 users have reported messages were missing from group texting threads, and the MMS improvements in iOS 14.2.1 should help address that issue.
Here’s how an affected user describes it:
I also have the same problem on the new iPhone 12 pro. It seems that it only happens in sms threads (where at least one contact is not an iPhone user) and certain messages are never received, which makes it impossible to continue any type of conversation.
And finally, the software solves an issue where some Made for iPhone hearing devices could have sound quality issues when listening to audio from an iPhone 12.
IMPORTANT: This update is available only for iPhone 12 users, not older iPhone users.
To update, simply open Settings> General> Software update and follow the instructions on the screen, if you have the automatic download option enabled, (this update is only available for the iPhone 12 mini, iPhone 12, iPhone 12 Pro and iPhone 12 Pro Max) will automatically download and install the latest update overnight, while the device is running and charging.