You're unable to connect your bank account, because after signing in your bank app, an infinite loader appears?

This is an issue that sometimes occurs when you use Chrome as your default browser. The good news, is that you can easily solve the issue by downloading a new browser (such as Firefox) and setting this as your default browser.
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On Android, you do that by going to Settings -> Apps -> Search for the browser -> Click on Browser-app -> Select the new browser as your default browser.