It seems like it's oxidized for some reason.
How did you store it, what did you put it in? Maybe some enzymes are in the solution?
Don't consider this safe right away but I've heard more than one person on this forum say that they had this happen with other tryptamines and didn't really get less effect from it. Only, when it happens when the compound is still undissolved, as a solid it can get very greasy when turning dark, making it almost impossible to weigh. You don't have this particular problem.
Hard to tell what happened or in what state it is in now, but it seems unlikely to me that it became a poison. Try like less than 1/10 of a dose and see if you get effects or side-effects, then
wait some days or a week and try somewhat higher.
But please tell us a bit more about the circumstances. And really consider if you want to take a chance with this stuff since obviously I can't tell from out of my comfy chair.
4-AcO-DMT and other tryptamines should not be stored in solution in the first place by the way, since it speeds up both degradation and oxidation, I believe. My solid undissolved 4-AcO-DMT has not degraded AFAIK (haven't checked the freezer lately).
I have kept my 4-HO-DiPT and 4-HO-MiPT away from light, oxygen, heat and moisture and last weekend used up a little 4-HO-DiPT. It was in great condition, couldn't be better.