I have seen in the internet, the Gimbal cover suppose to be remove before flight. Dont you think it is obstructing the gimbal movement?

Gimbal Cover DJI Mavic Pro UV ND 2 4 8 16 32 Neutral Density Lens Filter Protector Drone Accessories ProP Protective

There are gimbal covers that can be used during flight, because covers do not have internal plastic slot that locks gimbal in position for transport.
I have clear gimbal that can be used during flight.  Along with clear gimbal (marked Red) with internal plastic slots that must be removed before powering drone on.

You have to remove it, leaving it on there while flight will obstruct the air flow and overheat your drone.

Where are these sold and what do the sellers say about air-flow obstruction?

I've always taken my off during flight due to the air flow issues mentioned about. Always assumed that it was strictly to protect the gimbal during storage/transport. Not sure I'd use a gimbal cover where an ND filter is typically used.

Nice information

Dorset_Horn Posted at 2018-8-11 01:54
Where are these sold and what do the sellers say about air-flow obstruction?

you can get from aliexpress

I haven't used a gimbal cover and I don't recommend doing so since there is significant air uptake that occurs between the gimbal and the intake fan located behind it. If you block it with a gimbal cover and you're flying during the day with sunshine and high temperatures then it cause your Mavic Pro to have cooling issues?