The Connect a bank account popup checks, live, whether a bank account is actually on file every time the page loads — it doesn't remember that you clicked "Connect" before. It keeps appearing (up to once a day, for up to 90 days from when you first saw it, unless you snooze it) until an actual bank account is present in Accounting.

It only appears on your Dashboard (or the Catering Dashboard), and requires the Accounting module to be active, your role to have permission to edit accounting items, and that you're not currently in the middle of an onboarding walkthrough.