Yes, there are certainly banks that block more aggressively, but if you look at e.g. iodéOS's forums most of them work fine: https://community.iode.tech/t/banking-finance-and-insurance-...
Anecdotally, I've also seen a lot of stories of people reaching out to support about overblocking actually seeing success. Apparently there are often enterprise reasons for the block and it literally just needs a customer to complain for engineering to be able to act.
More info here: https://grapheneos.org/usage#banking-apps
My credit union wasn't on the list, but it works.
And beyond that, in some countries the strong authentication for logging into government services has been implemented through banks, and so one cannot visit one’s local tax-authority or healthcare portal without a phone that runs the bank app.
One example is my local bus company only selling certain tickets (monthly ones, for example) on the app. If you do not want to use an app you pay per trip which can be a LOT more expensive (several times as much for a daily commute).