This is probably going to sound really out there. For the last two development runs I have noticed that after dumping the stop and the fixer out from the tank I get this odor of what I can best describe as cabbage. The odor doesn't stay for long. These last two development runs I had switched from developing T-Max 100 to Catlabs 80 with my usual PQ universal process that I have been playing around with for about a month now.
As I've taken in the last few months to making sauerkraut, I clicked on the thread title with interest and curiosity.
Sadly, I'm at least slightly disappointed .
Perhaps you have confused your bottles of fixer and kombucha?
It has been my experience whether actually true or not, that "rapid fixer" sulfurs out more quickly than regular acid hardening fixer like Kodak Fixer. And even if it hasn't sulfured out noticeably, can exhibit all sorts of smells. And not always the common stinky rotten egg sulfur smell.