Did you ever check if your propellers are balanced?!
I have a good hear for sounds/noises (high school piano), casually I saw some videos with fake props or not, where I noticed the sound of the four props was not in synchro.. it can happens even with some motor a bit loose, or after an accident where it doesn't rotate well.. or, like a video I saw, where props are not balanced.
It's not a big problem but simply the drone doesn't work 100% as it should..there are tolerances of course..
Anyway, I can search again the video if needed..it's a simple object to buy but it can be made at home!

Can it balance the Mavic folding props.

you need the props removed from the drone to do so..