I've seen some people doing work on this [1]. I can't remember how much was actually making the drones quieter vs doing signal processing to remove the sound from on-board audio capture.

[1] https://www.dotterel.com/

If it's anything like e.g. PC fans, using larger, slower moving propellers is the way to go.

But alternatively, just use a selfie stick, the previous biggest nuisance.

In theory the noise is wasted energy, so making them quieter should make them fly better too.