What would cause this with 2600mm camera?

Clouds, fog, mist…

It seems you have a bayer pattern in the second one, which is kinda odd.

Hard to tell what overexposed is from stretched images.    What to the histograms look like from these 2 images?

Dan Kearl:

andrea tasselli:
It seems you have a bayer pattern in the second one, which is kinda odd.

Yes it does, I am afraid this was not a high cloud issue (there we're none).
I guess I wait for a clear night to find out but I am afraid it is the camera.

I have a pole master attached to the dec plate and take an image every 60 seconds so it's looking where my scope is. You'd be surprised at the high clouds that you cannot see are actually there. You can tell by obviously seeing the bright clouds that pass by but also by the varying intensity of the brightness from frame to frame. You may not see them, the weatherbug or whatever app will say there's none but it's very likely they are there.

Could be dew, high humidity, fog, I doubt it's the camera.

The bayer pattern could be from star alignment interpolation, if these are aligned images.