In this specific case it is. There is a direct correlation. One simply needs to do fifteen seconds of research into it - Datomic was the single strategic multiplier that enabled Nubank's success. Later they made an executive decision to acquire Cognitect to secure their critical tech element. They didn't buy the makers of Clojure simply out of love for Rich Hickey's hairstyle.
Your point about JPMC is silly - assets are not a customer base, and I said nothing about the former. If JPMC had grown its customer base at the same 10.9x rate as Nubank, starting from ~60M in 2019, they would have reached roughly 10% of Earth's population. Arguing against Nubank's achievement is like insisting on a flat Earth. Not attributing their success to their tech stack is just not knowing the facts.