Please get some clearer photos of the comb and the rooster/any other injuries as well.
I would not use any scrubbing action, peroxide or a toothbrush on a comb, wattles or face of a chicken.
If it's injury, then generally it will heal up on it's own. A tiny bit of triple antibiotic ointment applied to the comb if you wish.
If it's frostbite, then scrubbing, rubbing or messing with the comb will be painful and can make it much worse. You don't really mess with frostbitten tissue.
Peroxide can be damaging to skin, so it's not recommended to use. For a comb IF it absolutely has to be cleaned for some reason, then saline, vetericyn or banixx would be my go to products for anything dealing with face or comb.