I've been flying my mavic for a few months now.    Not all the time but usualy about once a flight I get a obstacle warning.   At first I thought it was sun glare but its not.

I know it's false as had it over open skies, no birds, no trees in plain sight.  Like at 25M high

Mostly it just scares me when it goes off, like I'm about to hit somthing.   Any way to correct this?

Unless it comes with firmware update, you could try calibrate sensors.

Easy - disable it.  I think it causes more issues than it solves outdoors.  Indoors it is somewhat useful.

It will also prevent a RTH in the event of RC loss if you are heading back towards the sun, so it could be a major hinderance too resulting in loss of the drone.