Went out for my maiden flight yesterday and am less than happy.
Seemed better after I took the lens filter off.

All I did after this when I got home, is to update the 2 batteries' firmware .. and calibrated remote.  Everything else was up-to-date at time of flight.

https://youtu.be/PPM-_LcAgH0    1

https://youtu.be/QJOu8sQCYyA   2

I hope it's something I'm doing wrong and is easily corrected.
Saw no warnings to not use ND filters ...?

It has nothing to do with using ND filters, most likely is a nicked propeller blade. Change your props to see if it fixes the issue.

Night prior to this flight, I had landed on a table and clipped the remote controller, it seemed fine ... apparently not.
I'll change out the rear right and see if that's the trick, thanks for posting.

FOUND IT , thanks again.

Hello there. I am sorry for the trouble this has caused and thank you for reaching out. Just a reminder that before each flight, it is necessary to check the propellers for cracks, wear, warp, corrosion, and loose screws. If any of these conditions are present, the propellers should be replaced. In addition I will post a DJI Forum threads created by SCoutts on DJI Mavic Mini Propellers - Inspect, Remove and Install ( https://forum.dji.com/thread-207043-1-1.html ) . Thank and fly safe always.