Bladder issues seem pretty widespread geographically with people around the world being affected. I don't know how to explain that unless the entire worlds supply of ketamine is coming from a single source (not that I know anything about the illicit ketamine supply chain, maybe it does come from a single source).Yeah, probably the easy availability of low price K in some places led to use we haven't seen before but some are reporting issues with just a few ten grams over a few months. Once I used 25g of Darknet K over a few days and got an agony of K cramps pain which 15x the amount of 2F DCK didn't remotely. So I'd say norket is urotoxic but only slightly and we have similar but much more toxic compounds in there or metabolized out of some synth leftover.
Illicit K is considered pure when it has some 84-86% afaik. That's not really a good value and leaves space for God knows what not.
Most samples on drugs data just show ketamine and leftover precursor whatever that entails.
I'd be inclined to side with the hypothesis that people just take a lot more ketamine these days and that's led to more reports of this kind emerging. Compounded as you said by cheap easy access to the drug but also by the fact that everyone has broadband and smartphones so word spreads faster than 20 years ago. What else can we assume unless something weird and identifiably bladder melting shows up in a lab test?