This has probably already been covered elsewhere - so apologies in advance:
I have been using the same camera settings for both video and still photos on a Mavic Pro with DJI ND filter usually attached.
Normally, I switch between shooting video and still photos during the same flight and maintain the camera settings (ISO 100, shutter speed either 1/60s or 1/50s, RAW format).
However, the quality of the still shots is not great.
To improve the still shots, would it be better to remove the ND filter (lighting conditions permitting) and adjust the shutter speed instead?
In other words: filter on for video, filter off for still shots?
... which would mean separate flights for taking stills and for taking videos.

Unless you want to shoot a long exposure for some reason I would recommend taking the ND filter off when taking photos.  This will allow you to use a faster shutter speed thus reducing any camera shake.