This isn't motion blur, stemming from accidental movement of the camera during recording or movement of the subject.
This is too shallow depth of field.
Phone cameras normally have such tiny sensors and focal length that they should, in theory, be able to capture everything tack sharp from front to back, unless you're moving in really close. If you have multiple lenses to choose from, pick the one with the lowest optical zoom, i.e. largest field of view. Also phone camera lenses sometimes are pretty crappy and will slightly blur everything near the corners no matter what you do. There's no fix for that except taking a better camera/lens. But maybe your lens just is a little dirty - give it a gentle wipe with a microfiber cloth. Oh, and check if you have something turned on or on auto that's called portrait mode. If yes, turn it off. And if you have a dedicated macro lens, don't use that either.