USB-C earphones turn volume to max (or zero)

[JBlack99]

When using USB-C earphones, the phone will act as though the earbuds are turning the volume up and will continuously hit max over and over. I swapped to a different pair of USB-C earphones and the same thing happened but in reverse and the phone spammed zero volume instead. This does not happen via Bluetooth and only when the earphones are used. Is my device defective? Charging works as normal. 

[Fiona26]

https://www.samsung.com/us/support/troubleshooting/TSG01001259/

Volume turning down once plugged in is normal. Should not stay to zero.
Try clear cache for the USB port. Then restart the device

From Settings, navigate to Apps, then tap the Filter and sort icon.

Move the switch to the right to enable Show system apps, then tap OK.

Scroll to USB Settings and tap Storage.

Tap Clear cache located on the bottom right-hand corner of the screen to clear your USB cache.

[JBlack99]

I have done all of what you have suggested already. This isn't a safety feature. On one pair, the volume goes to max and the device vibrates constantly as if the volume is being actively turned up. The other pair do the opposite, and the device vibrates indicating the volume is being turned down. This does not happen when using a pair without volume control, but then the volume doesn't work at all on that pair.

[JBlack99]

If I can somehow link a video I could demonstrate.

[Fiona26]

You could check if it still does it In safe mode

https://www.samsung.com/us/support/answer/ANS00062983/

It will rule out the possibility of a third party app causing it.