Last week, a federal court struck down the Federal Reserve’s Regulation II debit interchange fee cap, upending a framework that defined payment economics for more than a decade. The Consumer Financial Protection Bureau (CFPB) paused its open banking rule under Section 1033 of Dodd-Frank and delayed small business lending data collection under Section 1071, both responding to litigation. The Supreme Court’s Loper Bright decision eliminated Chevron deference, sharply curtailing agencies’ ability to interpret ambiguous laws. From a distance, this looks like a deregulatory moment. For many fintech business models, it creates a high-risk period of uncertainty that can be more damaging than the rules themselves. The Regulation II ruling illustrates the problem. Companies that built their economics around debit interchange fees now face uncertainty. Some use those fees to fund rewards programs. Others share them with banking-as-a-service partners or use them to offer zero-fee accounts. The Fed could rewrite the rule to favor merchants, which would slash interchange rates. But that process could drag on for years, with appeals and maybe even congressional hearings. Meanwhile, companies are trying to plan budgets and investor presentations without knowing what their core revenue stream will look like. This pattern extends beyond payments. Credit card rewards, routing rules, and data rights all face similar risks. When a business model depends on a particular legal framework, and that framework gets sent back to the drawing board, companies operate in uncertainty until something new emerges. What’s likely to emerge is fragmentation. Private companies will cut bilateral data-sharing deals. Different states will write their own rules. Banks will use different technical standards depending on who’s asking for data. For fintechs that need bank data, the complications are significant. Integration costs increase. Product launch timelines extend. And there’s always the risk that key data sources will change terms or cut access entirely. Recent developments illustrate this risk, with major banks beginning to charge fintechs for customer data access through aggregators. Industry executives warn these fees could be devastating for early-stage startups and make certain financial transactions economically impossible for consumers. Without clear federal rules, banks can essentially set their own terms for data access.