I am still don’t fully (?) understand the use of རེད་འདུག …
For example here, supposedly the person is describing her/his house, and that supposedly doesn’t have some kind of surprise. …
So it means the speaker is identifying the color of the house, which is a general feature of the house (རེད་). But they are also personally experiencing or noticing or realizing what that color is right now (འདུག་).
So maybe they are just noticing that, or maybe they had thought it was a different color before, or maybe it’s kinda new info for them… རེད་འདུག་ and རེད་བཞག་ work a bit like that.