Heck I am Male And know that peroxide is uaed to bleach hair. Do you have any teens in the household, some will bleach the new hair growth rather than shaving, girls on their legs but even boys on 'peach fuzz'~gd
Did the OP rule out that her bathroom towels might not have been dyed right in the first place?
See my note regarding the fact that it has been 4 different sets of towels by 4 different makers, a couple of which are very good brand names (landsend probably being the best one)
So I really suspect that it isn't the quality of the towels themselves.
I will change our habits handling our saline and make sure to dry off hands and the bottle and contacts cases with one of the plain white washcloth rags rather than the hand towels now, and hope that fixes that problem. Another one of the larger towels that was bleached I don't know about, it must have faded out for another reason.
So frustrating.