Yes they did. Trello leaked usernames, full
names, “other account details” in exchange for an email address input. Credential stuffing requires knowledge of the password.
Trello reveals these via their "share" functionality. Put in an email and you get a name and username. This isn't a leak. It is designed that way.
So let me try to "share" something with on a banking app, see if that returns your balance. And then I'll tell you it's designed that way after I publish it along with 15M other people's balance. Not a leak guys !
Credential stuffing can use the password, but in general it's just using some credentials you already have (maybe just an email) against a different service to see what you get out.
Can you just admit you’re wrong here? If I go to a service with 1 piece of information (an email) and I walk away with more PII than I provided, that’s a leak.