Are you having trouble answering your phone with the iOS 14 update? Several people have asked about an 'issue' related to not being able to answer a phone call. They reported that the answer screen does not always pop up in iOS 14 unless your screen is locked.
Reason for Change
iOS 14 has a new default screen that takes up less space on the screen; the phone call appears in a banner at the top of the screen instead of taking up the full screen. It is designed to enable you to keep looking at the app you are currently using while answering your phone.
Do you want to go back to the old, full screen? Simply change the phone call alert from the Banner style to the full screen style. Go to settings > phone > incoming calls and select Full Screen instead of Banner.
Note: When VoiceOver is running, use a two-finger double tap anywhere on the screen to answer or hang up a phone call. The people who are asking about the banner vs. full screen change have self-reported that they tend to swipe right and double tap when VoiceOver announced Answer.