That particular picture doesn't look like it's real to me, even now after seeing the video on the dark face budgies.
Maybe it's because the colors in that bird look's picture "too" vivid? 🤷♀️
For sure about the genetics with regard to that mutation though!
After I initially replied to you, I started thinking about it and realized I had heard something about a "rare dark face mutation" so I had to search for it.
I'll remember the next time someone asks!