There are touchscreen issues affecting the lockscreen, so you should try and wait until it’s fixed

The iPhone 12 mini may have been announced last month, but people weren’t actually able to get one until last Friday (November 13). It’s been quite a long wait, and to make matters worse new iPhone 12 mini owners are having problems.

Large numbers of people are reporting that they’ve been suffering from issues with touchscreen sensitivity on the phone’s lockscreen.
…
Continue here:
https://www.tomsguide.com/news/dont-buy-an-iphone-12-mini-just-yet-heres-why