Hard to know exactly what you’re talking about… If you’re talking about how some lenses have this kind of distortion and indeed blurriness the further away from the center it is, this is a result of lens selection. Typically you’ll notice this more strongly on fancy anamorphic lenses that cost obscene amounts of money trying to reproduce defects of OG lenses of yesteryear like Cooke etc. There can be many reasons the DOP would choose these lenses but mainly it’s because they help keep the focus on the subject and create interesting backgrounds that are still subtle enough to not be distracting to most viewers. Personally I prefer technically good lenses with sharpness across the frame but this style of lenses is certainly extremely popular at the moment.