I am not sure what I did but the “chrome” around my app is a brown - the theme is the same on all devices and on a second Mac it is fine. I am sure there is a silly reason but I can not find the location to change it.
What happens if you change the Drafts theme?
Does it show like this for other apps too?
Is your desktop background different on the different machines? Big Sur’s window translucency may even be at play I guess.
That was it - The odd thing is if drafts was on top of a near full screen of say an app with a white background the color did not change. The desktop was what was coming through. Thank you it was making me crazy