Hello
I recently bought the Galaxy A21s and I noticed that when it's lying on a flat area the top of the screen doesn't work I can swipe and unluck my phone but I can't swipe down the notification bar unless I pick up my phone and also the touch sensitivity gets low when holding in a specific way especially in landscape mode.
I was just wondering if all the A21s share this problem or the problem is from my phone only ? also cuz it's new they didn't have a protector or a cover and they used A71 protector I wonder if that's the problem?

Go to setting / display / turn on sensitivity switch. This will solve your problem. This will unlock Samsung screen properly with fingers.

regards,
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