[judge2020]

Google, Duo, and Authy all seem to do fine even in low-data (1 bar non-lte 4g) scenarios, so that's probably a bank & facebook issue. They probably rely on the push notification to carry and push state to the user's device with no backup mechanism for when this fails.

[withinboredom]

Of those three, I've never had an issue -- and I pretty regularly wander around with 1 bar non-lte quality service.