Chime found a way to offer zero-fee banking services without being a bank itself. But that approach is starting to show its limits.

While Chime brought in more than $1 billion in revenue last year, according to two people familiar with the figure, Chime’s revenue growth has slowed dramatically since 2020. And behind the scenes, the startup that once fetched a $25 billion valuation has struggled to fix costly fraud issues and long-running problems with its core technology.