Diagnosis
Yeah, this one's common. The monitor's internal 5W speakers are notoriously bad and prone to electrical interference, especially if you're using USB-C for both video and data. The buzz is often a ground loop or interference from the video signal.
How to Fix It
The real fix is to not use them. Use your computer's audio out, external speakers, or headphones. If you must use them, try isolating the audio source. Use a standard HDMI or DisplayPort cable for video instead of USB-C, and see if the buzz disappears. You can also try plugging the monitor's power brick into a different outlet than your PC.
If That Didn't Work
Go into the monitor's OSD (Settings -> Sound) and ensure 'Auto Volume' and any sound enhancements are turned OFF. Sometimes these cheap DSP circuits introduce the noise.
Heads Up
Cranking the volume above 60-70 on these speakers can cause the thin casing to vibrate and create a distorted rattling sound on top of the buzz. They're truly an afterthought; don't expect any quality.