Some banks require you to relink your bank to external companies, like Starship. This can happen at different times depending on the bank - could be once a month or every few months.
When this happens Starship will let you know the next time you log into the app. You can also view this at any time by logging in and tapping on Profile, then linked bank account. You will see "Unverified" next to your linked account if you need to reauthenticate. Just tap on it and follow the flow.
**Note, when your linked bank expires, things like Round-ups and automatic contributions will not work so if you want to keep your savings on autopilot you'll need to check on that and ensure everything is in the green.