I am using tap water, so I shouldn’t add any h202?So this is where opinions take over.
If this were me, I would start by a full water change. If you are using tap water, it already has chlorine or similar in it. If RO water, then I would add 10ml 3% H2O2 to the res water per gallon, no nutes just PH'ed and let it run for 1 day. Take a close look tomorrow and post pics. The expectation would be to do it again tomorrow, but this time add the nutes back in. You may end up dropping H2O2 as well depending on what you see.
Peroxide does damage the roots as well so you don't want to over do it.
If it looks improved tomorrow, add the peroxide treatment to your normally scheduled water changes until you harvest. I find these helpful when running sterile: