I have B2B and B2C fintech experience (USA only, nothing international). The consumer side, there are gangs, the ones I knew were 'from' eastern europe and were physically located in specific areas of the USA. Aside from them, it was mostly one off stuff that we could eventually predict via better analysis of credit profile. Surprisingly, welcome calls, with well trained staff, were shockingly effective at stemming fraud, as was having a specially trained group of customer experience folks who specialized in detecting fraud.

On the B2B side (white label financing) there were significant fraud problems that were sometimes not detected until far, far too late. We relied on individual account manager's ability to train, and closely monitor, the partner companies. Interestingly, we would detect the fraud first from either word-of-mouth through the grapevine stuff gathered from our sales & management team via industry chatter or account manager relationships, or from various kinds of data analysis. Impact was maybe 1-3% of gross revenue, depending on industry and scale of operation. Really really depends on the sectors you are working with in B2B fintech, some are shadier than others. like... used car financing? good luck with that