There is already a parameter to adjust this in UserCfg.opt called EyeAdaptation
By default it is set to 1, but there is no way in the UI to change that setting.
By editing userCfg.opt before starting MSFS and a bit of messing about with the server syncing), you can force this parameter to be 0 when the sim is running, and this greatly reduces the effect - so much so, that it might even be turned off if it was set to 0.
Interesting, is that with it OFF, the effect is still slightly there, because of what your eye is doing… with a bright outside, the panel does appear to get darker, but if you keep that view with the bright outside, and just cover it the bright area up on the Monitor, the cockpit appears to your eye, to get slightly brighter again.
So, maybe all that is needed is a UI control Eyeadaptation ON / OFF ?
The good news is that there is a possible workaround.
Same applies to Fringe 1 !!! which really messes up certain parts of the hangar windows frames etc etc ( No UI to control this)
No idea why it is even there – it looks like an attempt to make image look 3D, if you wear red/green 3D Glasses ??
Anyway, that can also be over-ridden by editing the UserCfg.opt file, EVERY time before you start the sim. (when you close the sim, it gets written back with original default value of 1)
If these edits are done within a startup script,( bat file) that does these search replaces, before starting the sim, its quite painless.