Bezels often fade, or degrade. Some bezels go grey, and some are dipped in bleach to achieve a “Ghost” effect. I have seen blues, on older Speedmasters, and saw a green one last year.
Rolex bezels have been seen in faded brown, but so far I have not seen a brown bezel on a Speedmaster until now:
This is a later 145.022-69, and so the bezel has the correct, DN90 dropped serif layout.
I just dont know if this face is man induced or through natural aging.