Warn? Yes. Refuse access? No.
I would close my bank account over this. That’s not saying much though because they literally pay you to open new bank accounts these days…
If you cared even slightly about the app, you wouldn't have a HSBC account anyway, you'd have Starling or Monzo or maybe Revolut
If you cared even slightly about the app, you wouldn't have a HSBC account anyway, you'd have Starling or Monzo or maybe Revolut