I have heard this about ‘oxidised’ before (mostly Hoffmann repeating something George Howell said, but I haven’t seen Howell’s cold brew recipe) can you describe a flavour attribute that you know is solely from oxidisation? Are you sure you are getting the same extractions between hot & cold?
I have compared overnight (hot bloom) cold steep with fresh, flash chilled and hot coffee. I can’t detect anything I see as oxidistion, the significant difference is in the bitterness of the hot brew. Extractions are broadly equivalent, which I don’t typically see people do (most set out to make different coffees, which would still be different if both were hot, r cold).
Clever Dripper small - 13-14g of coffee around 70g/L, V60 grind, coffee in first, hot bloom with 30g water for 30s, then another 30g hot. At 1 min add remaining cold water and steep for 8 hours or more. I guess you could double up weights for the larger Clever as it holds twice as much in the well, but not tried it yet.