It really isn't/ shouldn't be. In theory, the bank is really incentivized to provide proper and secure authentication (if someone can impersonate you to your b

It really isn't/ shouldn't be. In theory, the bank is really incentivized to provide proper and secure authentication (if someone can impersonate you to your bank, you're kinda screwed anyway). So, it only makes sense to trust a bank to provide the authentication service. One should realize that SSO integration with a bank doesn't mean 3rd party has any sort of access to the bank - it' just means that you authorize your bank to tell a 3rd party "yes, I believe this is really curryst"). Doesn't increase the attack surface for you - it only increases the "blast radius" if someone successfully compromises your bank account. But that one is typically already a dire situation.