Stripping color from 1/6 clothing- help needed

So I have an old Sideshow Frankenstein jacket (Green) that I want to strip to dye brown. I used RIT color stripper and it started striping the color perfectly and faded it to the perfect brown I wanted (so no need to re-dye). I let it sit in the hot water for at least 10 minutes, then took it out and rinsed and immediately the jacket reverted back to the original green color. Since the color faded inthe RIT solution it seems it's not polyester, but a material that can be stripped. Should I leave in soaking longer? What went wrong?

Sean

Wish I could help sorry kinda want to do the same thing but I'm gonna try to remove blue dye and re-dye it red. doing some research before I even buy the jacket I want to attempt it on. Trying to see if it is possible or if I'd just be wasting my money heh.