It sounds like there’s a little motorcycle riding around in my earbuds. The frequency changes with the brightness of the screen. I play 100% with headphones so I have to return it, but if they all (or a significant percentage) of OLED units have this problem then I’ll just return it and not get another one right now.
Edit: it’s good to hear that not everyone has this problem. I’d be curious for those people who aren’t having the problem to test with a bright white screen. Mine gets worse as the brightness of the screen increases.
Edit 2: I used a MillSO 1/4” to 3.5mm adapter and my Sennheiser HD558s and I can’t hear the buzzing like I can with my Apple earbuds.
Mine has it very badly. I suggest those that says they don’t have it or hear anything, it seems more apparent when there is some audio signal coming through so try playing something at very low volume so it doesn’t mask any static noise out and try focusing on it. If you’re just plugging in and not having any signal coming through then you probably won’t hear anything or have very low noise. More noticeable on earbuds than normal headphones as well.