Using MacBook Pro (2020, 4 thunderbolt ports) with this USB-C to 3.5mm Headphone Jack Adapter, would usually face distorted sound or even muted halfway after a buzzing sound was heard. It was temporarily resolved by removing my earphone from the adapter and plugging it again.
MacBook
Hi,
I suppose it's an adapter's problem, try to contact Apple support or make Genius Bar reservation or take the adapter as well as MacBook Pro to Apple Authorized Service Provider to be examined it before limited one year warranty is over.
You could replace the adapter with new one.
https://support.apple.com/contact
hhttps://locate.apple.com/findlocations
https://locate.apple.com/findlocations
Apple USB-C to 3.5mm Headphone Jack Adapter
