Login issue: cannot log in on iOS <16.4
Known Issue
Following framework updates done by our authorization provider, the minimum version of iOS required by their services is 16.4.
If you are able to update your device to at least iOS version 16.4, this immediately remedies the issue, but they have confirmed that devices running older versions of iOS are no longer supported by their services—or Apple's—due to the compatibility and security risks.
There is no other workaround at this time.