Tilt-shift lens?
Or to be more accurate, faking using a tilt shift lens in entirely the wrong way... A tilt/shift lens will avoid that effect, in fact that's half its raison d'etre.
I'll declare my view here, I absolutely hate that effect, it absolutely screams "fake" to me, in a very shrill tone.
Yes, I do possess a tilt/shift lens, and no, I'd never use it ass back'ards. If I want a narrow depth of field to isolate my subject, I'll use a large aperture.
I think its all a side effect of folk thinking a phone can do everything a proper camera can. No, it can't. Its a useful thing, but for creative photography, of limited use.