I have the same problem (Surface Pro 6 with Windows 10 Build 1909):
With the audio playback device Surface Earbuds Hans-Free AG Audio connected via Bluetooth LE i constantly hear disturbing noises only on the left headphone. No matter in which application (Microsoft Teams, Spotify, YouTube, ..)
If I connect the Earbuds with a Smartphone or iPad, I don't have this phenomenon with the noise! Updates, resetting to factory settings, reconnecting, everything does not help. How can that be? It works with Samsung and Apple-Devices but not with the Microsoft
Surface? Are you kidding me?
But the following is interesting: As soon as I switch to the second audio playback device (Surface Earbuds Stereo) in Windows 10, the sound is good without disturbing noises. But, this device only works as a stereo playback device without a microphone.
In the sound settings of the corresponding headphones you can see: 2 channel mode, 16Bit and 44100Hz.
In Microsoft teams I can set Surface Earbuds Hans-Free AG Audio as audio device in the device settings. This is how the microphone works, but the sound sounds awful with disturbing noises. Another setting does not work with the Earbuds.OMG.
I also noticed that in Control Panel > Sound the following is set for this audio device: 1 channel, 16Bits and 16000Hz. What also surprises me is the relatively old Bluetooth driver in Windows 10:
driver name: microsoft_bluetooth_hfp.inf
Class GUID: {4d36e96c-e325-11ce-bfc1-08002be10318}
Driver date: 03/18/2019
driver version: 10.0.18362.1
Driver provider: Microsoft
Driver section: Common_BthHfAud_Install
Driver rank: 0xFF0000
Suitable device ID: BTHHFENUM\BthHFPAudio
Common Microsoft, you should fix that issue very soon.