When I swipe down or when I try to use the search bar by screen goes blurry like this.

Found this solution in another forum. It worked for me. Sooo happy cuz this happens to me often.

if/when this happens, put your phone to sleep/lock the screen.

Wake your phone, but do not enter it.

(for Face ID models this is really simple because you just don't swipe up to access your Home Screen)

(for Touch ID models, I'd suggest waking your phone with a finger that won't unlock your device)

Swipe right to access your Today View widgets from the Lock Screen.

If yours is the same as what I came across, the search field will be displayed and the cursor captured in the search field rather displaying the widgets.

Simply tap 'cancel' next to the search field, now the widgets should be shown.

Access your phone like normal now and try searching again by swiping downward on the Home Screen.

For me this fixed it.