In February 2019, I received some Metol from my, usually very reliable, supplier that was a light tan colour. I have never seen this before. However, I tried using it for my usual developer (Barry Thornton’s Two-Bath developer) and, initially, it seemed to work. However, within a week, the developer had discoloured badly and a test roll of film showed that the developer had lost a great deal of its capacity (films were severely underdeveloped).
I posted on this site and talked to several other photographers here in Germany who make their own developer and all had experienced the same problems with dramatically reduced capacity from the light tan coloured Metol from the same supplier. All said that it worked fine at first but then quickly discoloured to a point where they did not want to use it for fear of ruining their films.
One of the people I talked to was Wolfgang Moersch (
https://www.moersch-photochemie.de/content/news) who makes and sells a wide range of interesting products. He had tried the discoloured developer and found that "the only directly visible disadvantage is the grey colour of the solution and a dark, uncomfortable precipitation at the bottom of the bottle. Such solutions are still effective, but I cannot guarantee that exactly the same densities will occur during film development" and this pretty much mirrored my own experience.
I then contacted my usual supplier and explained the situation. They sent me a new batch of Metol for free that was white in colour and worked exactly as expected.
Your Metol looks far worse than mine was so I would firmly say that your Metol is not good and you should send it back immediately.
Bests,
David.
Temporary website address:
http://dsallen.carpentier-galerie.de