They mitigate the obvious security thread with mandatory 2fa (actually mandated by regulation). Some use this as an opportunity to push their apps: no separate 2fa method, but only integrated in their bloated app, that checks for rooted devices and only supports the newest OS.
It’s quite hard to find out in advance, what 2fa methods with which fees each bank actually requires. I remember that some of them had funny ideas, what a customer should be billed for 2fa SMS. I think it was 50 cents per SMS.