This morning I used Nubank to send a Pix payment to my neighbor. The interface had changed. Instead of entering the recipient's key and seeing their details upfront, I was asked: "How much would you like to send?"
First problem: I hadn't confirmed who I was sending to yet.
Second problem: how do I answer? "60"? "R$60"? "60 BRL"? I wasn't sure. I cancelled, tried again with "R$60". It worked. Later that day I sent another payment and typed just "160". That worked too.
Same interface. Different inputs. Both accepted. No guidance either time.
So I got curious. I entered an invalid key — just to see what the AI would do with it.
It said: "Sorry, I couldn't detect the Pix key. Please tell me the type so I can process it correctly."
The type. Of a key that doesn't exist.
A form would have just said: key not found.
The problem with conversational UX in structured flows
AI-native UX doesn't mean turning every flow into a chat. It means knowing when conversation helps — and when it gets in the way.
Payments are one of the clearest cases where conversation does not help. When I send money through Pix, I don't need the app to ask me conversationally how much I want to send. I need to see the key, the recipient, the bank, the amount, and the final confirmation clearly — in that order.
A conversational layer does not automatically make a flow more human. Sometimes it just hides the structure users rely on to feel in control.
Three things that broke
The new interface introduced at least three distinct UX failures:
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Confirmation order reversed — I was asked for the amount before I could verify who I was sending to. In a payment flow, recipient confirmation must come first.
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Input format undefined — "How much would you like to send?" gives no indication of expected format. The interface accepted both "R$60" and "160" without explanation. That inconsistency erodes trust, even when it works.
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Error handling regressed — When a Pix key doesn't exist, there is only one correct response: key not found. Asking for the "type" of a nonexistent key is not helpful. It's a conversational response to a problem that conversation cannot solve.
When conversation helps — and when it doesn't
Conversational interfaces are genuinely useful when users need to explore, clarify, compare, or decide. They work well in ambiguous situations where the system needs more information to proceed.
But many product flows are not ambiguous. They are structured actions with a known sequence: identify recipient, confirm amount, review, send. Wrapping that sequence in a conversational layer doesn't simplify it. It removes the structural cues users depend on.
Payments need visibility, predictability, and confirmation. Not a dialogue.
The real question
The question was never "should we add AI?" It's "where does AI actually help?"
AI in a payment flow could genuinely help — by detecting unusual recipients, flagging amounts that look wrong, or catching input errors before they become transfers. That's AI working in the background, making the structured flow safer.
What it shouldn't do is replace the structure itself.