When searching for an app on my iPhone I get a black, blank screen On my iPad, if I want to search for a specific app, I pull down from the top of my homescreen. That brings up an input pane to enter the name of App i'm searching for. The same method should work for my iphone but instead of screen input pane, the entire screen turns black and there is no way to enter the name of the app.
I have an iPad Pro running 14.4 and an iphone 11 running 14.4
How do I search for an app on my iPhone?
From Use Search on your iPhone, iPad, or iPod touch

Swipe to search

Swipe down from the middle of the Home screen.
Tap the Search field, then enter what you're looking for. As you type, Search updates results in real time.
To see more results, tap Show More or search directly in an app by tapping Search in App.
Tap a search result to open it.


Emphasis added by me on step 1.

If the above default method is not working for you, then restart the iPhone and see if the issue persists.