It's not there that I've ever seen in my 35mm R09 negs or when I stop my current reversal process and fix at neg. stage. I'm not sure where else I can stop the process and inspect the results. After bleach and clearing there's nothing useful to see, is there?
As I wrote there are many things that can cause the brown tone. If the bleach somehow forms Sulfide or precipitates MnO2 you should see that very clearly.
Trying to be the best of whatever I am, even if what I am is no good.