cotton and polyester puma sock I washed with some pooped underwear, so I don’t know if this sock looks brownish due to fecal matter.
I used a cold cycle and abundant detergent. Every other undie looks fine.
I don’t know if I should leave the piece to rinse in a cold water bucket with some detergent and wash again.
I believe you are talking about the yellow discoloration. That’s from leaving the clothes dirty for an extended amount of time and when you wash the detergent turns the stains yellow instead of removing them. You are letting your pile of clothes build up too long.