Hi @relero90
Thank you for letting me know!
You are correct, this seems to be the expected behavior, as I am getting the same result after reproducing. After researching on the matter, when having multiple Databases enabled for an application, Auth0 will default to the the first one.
To overcome this, you will need to pass the connection parameter in the /authorize request indicating the name of the connection the user should be logged in against for the signup flow.
I recommend reading through the following Knowledge Article on Associating multiple database connections with 1 app, that contains other resources that should be helpful on this matter.
Let me know if this worked for you!
Gerald