If we use swipe gestures for navigation bar, while on call we can not minimize it if the phone is locked. So we can't unlock the phone and use it as normal while on call.
What should be: Minimize the call, unlock screen will show, unlock the phone and use it as normal. This is how it was on one ui 4 and with normal navigation bar.
Well this is not exactly idea, it's a bug. But there is no such category to report bugs. I filled error report tho. I asked some friends with german beta and they do not have that bug. Thanks for your answer.