Your UI is set up such that it appears like it is asking for users' Patreon credentials. I see now that that was not your intent, so I apologize for making assumptions.
With that being said, asking for a password on a blackbox interface is just not the best way to go about it in my opinion. You've described your backend to me, and I believe you. But the current setup is going to easily confuse users into typing in their REAL Patreon PW into your app. Some may even do it out of sheer laziness. If you ever experience a data breach in the future, some of those REAL patreon credentials will be leaked. It's just not secure.
Research how to set up OAuth with Patreon. I believe it's a service they provide. That way users are redirected to Patreon's actual website, where they can log in with their regular Patreon credentials. Then all your DB is storing is non-sensitive info like tokens and login times.
Again, sorry if I came on a bit strong in my first comment. I'm a web dev myself, so i know how easy security is to overlook when your main focus is on the product itself. I also know just how quickly bad security can bite you in the ass if you aren't careful. Good luck.