What you see is one of the lower plating layers. For years Merkur have a triple plating process. Copper , nickel and chrome on top.Interesting. I thought I read somewhere that it's made of brass. There's also a spot on the handle where the chrome plating has slightly thinned and I can see copper color underneath. That said, I think copper is one of the "ingredients" in Zamak, so that could be what I'm seeing.
Look here at the descriptions of the razors on the Merkur site. Safety Razor Onlineshop - MERKUR Razors - https://merkur-razors.com/product-category/safety-razor/?lang=en
The other ones say brass handle, die cast head (with the exception of 41 and 42, which
are zamak handles).
The Futur says only die cast zink, which is an euphemism for Zamak.