Electric scooter chains tend to be fairly loud especially considering that they are practically the only part making any noise at all on the scooter. I would expect a good amount of mechanical noise to come from the chain when the scooter is being driven and the faster the scooter is traveling the louder the chain noise will be. However if the chain noise is abnormally loud then there might be a sprocket tooth that was cut wrong which the chain is catching on or a pin in the chain that was riveted too tightly and is causing the chain to bind.
To further diagnose the problem I would carefully inspect the sprocket teeth to make sure they are all uniform and none of them look different from the other teeth on the sprocket. Then I would remove the chain and bend each link by hand to see if any of the links are binding and not free to move by hand without using force. If the sprocket teeth and chain both check out okay then the next step I would take to lower the chain noise is to use a wax based chain lube which should lower the level of noise that the chain makes compared to using an oil based chain lube.
No matter what chain lube is used there will be a significant amount of chain noise when the scooter is being driven because on a fast electric scooter like you have with a 48 Volt 1600 Watt brushless motor the chain is moving around the motor sprocket at around 5600 RPM which is fast enough for any chain to make a lot of noise.
thx Support, I finally got fed trying to make it work and took to a scooter mechanic. My guess is something like you suggested on the sprocket tooth. Some of this stuff from china is cost effective, but really lack on quality control. Appreciate your advice!