I just rehabbed this exact bag (precreed also) too but I didn’t know the hardware was plated and I used brasso and steel wool! I can’t really see anything wrong with it (see pic). As a newbie, what did I do to the hardware unknowingly?
I don’t have a before pic for mine but I did similarly to you but warm water for 20 minutes including rinse and scrub. Reshaped and 3 coats of cpr with buff inbetween and a coat of Blackrocks. Took the hardware off and used brasso and steel wool. I did dunk the straps too. On the strap hardware I didn’t use brasso or steel wool, just some vinegar and using a toothbrush to scrub while in the bath. Mainly because it looked clean and I was lazy... I hate polishing.