I’m late to this post. But have a 2019 pathfinder that is having the same issue. Regular oil changes, but my engine is full of sludge at 51k miles, and is in really bad shape. Car was fine, then about a week ago, had to brake hard, and got a billowing white cloud of smoke pouring out of my exhaust. It stopped as soon as I accelerated. Happened again the next day, and has progressively gotten worse. First mechanic said it was a build up of moisture. So wrong. No one can seem to tell us the cause, or if it’s even fixable without replacing the engine.