Oh I just thought of something more likely. He probably is dominant white, blue, and barred.
Oftentimes barring can be seen on dominant white but if you had blue in addition to that it would be hard to see.
I would expect to see barring on his orangey feathers but that doesn’t always occur.
Is this a blue chick or a barred one or both?
Perhaps your rooster is actually splash rather than dominant white.
Maybe splash hides barring even better than blue.
Do you have any white birds?
If blue birds looked almost black they would not hide barring, it is the dilution that causes that.
I am thinking it most likely that your white birds are hiding blue and barred, if you have any white birds.
Orpington was definitely the father. Whites carrying funny unexpected colors are super common.
I hatch a gazillion chicks a year and I’m afraid/proud to say there’s nothing very odd or unpredictable around here. Except that last year every Buckeye pullet I hatched had some amount of black...