I definitely wouldn't use colour developer that looks like this. When I first started doing my own colour processing back in the 70s, I used Photocolor II kits, where the developer came as a one-part concentrate (like the developer in your picture). Here in South Africa the demand for these kits was quite small, and they tended to sit on dealers' shelves for quite some time. PE and others have from time to time commented how single part colour developer concentrates age quite rapidly, and this was my experience with a couple of newly-bought kits where the developer had already become substantially darker than pale straw (or white wine, as the Photolcolor II instructions referred to the color). After a few reels of underdeveloped negatives I refused to use developer that looked "like sherry" (again according to the Photocolor instructions) and returned the kits to the shop.
I know there are quite a few black and white developers that still work perfectly well after having turned the colour of Guinness
, like those you mentioned (another one is Rodinal), but that is definitely not the case with colour developer. The same applies to E6 first developer, which will begin giving you underdeveloped (dark) slides as soon as it's become noticeably darker than pale straw -- but there you can still compensate to some extent by increasing development time.