Anyone know how to remove strange stain from end of blazer sleeve

[inaba]

So I noticed there's this weird brown stain on the end of my blazer sleeves. It's on both sleeves and it's only on the top of the sleeve. I really don't know when I got it and I can't even think of how it might have gotten there. The fabric is 82% polyester, 16% viscose og 2% elastin and I'm tempted to just chug it in the washing machine since the washing label says 40 or below wash without bleach and low temp ironing

https://i.imgur.com/qMevFy7.jpg

My camera can't really capture it, but it looks even browner in real life

[binch]

im no tailor but that may be the fabric color oxidizing - in other words, something may have bleached it. Was it stored near any powders or wash detergents?

[inaba]

Nope. It has been stored in my closet when not in use

[mikerocks]

"Typically, if a stain is brown, it is protein-based and needs a product with the enzyme protease as an ingredient." I found that after looking some googling. There is probably a spot stain remover but I have no idea what it could be from.

[inaba]

Will try and see if I can find some!