2008 Santa Fe "buzzing" sound on acceleration

My Santa Fe has starting this high pitched buzzing sound when accelerating, particularly when going uphill. I goes away after resuming speed. I had a “yellow” in the maintenance category for power steering fluid that was dirty last time I was into the dealership for another issue. . Could this be the cause? Before the noise started, I asked at my last oil change (not at the dealership) about the dirty power steering fluid issue. They had never seen this as an issue before. How could the fluid be getting dirty?? Is it related to the noise?