DIAGNOSIS That's coil whine. It's coming from the power supply board inside the TV, where electrical components (inductors/coils) vibrate at a high frequency under load. It's not dangerous, but it can be irritating.
FIX First, identify when it happens. Is it constant, or only with bright scenes? Try lowering the TV's backlight/brightness setting. Go to Settings > Display & Sounds > Picture > Advanced Settings. Reduce the 'Backlight' or 'Brightness' slider by 10-15 points. Often, reducing the power draw on the supply lessens the whine. Also, enable any 'Energy Saving' modes, as they lower overall power.
IF THAT DIDN'T WORK Check your audio setup. If you're using the TV's speakers, the buzz might be electrical interference picked up by the internal audio amp. Try using an external soundbar or speakers via optical or HDMI ARC. If the buzz stops, it confirms an internal grounding or shielding issue.
HEADS UP Coil whine is a common manufacturing variance, not a defect that typically qualifies for a warranty return unless it's extremely loud. It often lessens over time as components settle. If it's a new TV and unbearable, contact Amazon support within the return window.