Shimano nexus roller brake noise - left brake on descent

Has anyone had this grating noise coming from the left brake/front wheel? It is on a relatively short - quarter mile descent going under 10 miles and hour.

It happens when I am coming back to my house. I am gradually slowing down so I can apply both brakes together smoothly to come to a stop.

I squeeze - squeeze and the the front brake sounds off. I continue squeezing both to a sudden halt. Not smooth or silent.

Is this normal? I have a brand new Electra Townie Go 8i?

Does it need Shimano grease on just that brake?

Thank you so much.
Thank you, Angela for your kind response. Can you ask Court if has ever experienced this noise with any Ebike that uses Shimano Nexus Roller Brakes? I know he is busy. Thank you again young lady.