That actually explains it for me, thankyou, I could see it was a transition but couldn’t quite work out from what to what. Flat grain to end grain explains the entire look. It’s as smooth as any other part so no issues then, cool.Looks like it's the flat grain of the mahogany when it's sawn.
Maybe flat grain does'nt take the colour of the filler as well.
It's funny to me as from time to time i see this pop up on threads and i strain my eyes to look for the imperfection and i can't see it - no disrespect . I just am so used to looking for the obvious flaws and stuff our eyes are trained to see from so long ago in a distant and far away galaxy .It's just the wood. May not be desirable to the really anal retental or OCD crowd but there is nothing wrong there.