Some iPhone users have been having trouble logging into their various apps since the rollout of iOS 13. The in-app authentication request for bank accounts, password managers, and other apps simply won’t appear on phones that have been affected, seemingly barring users who are unable to perform the Touch ID or Face ID login needed to gain access to their accounts.
The bug only seems to affect older iPhone models that are still equipped with Touch ID. Newer phones that only support Face ID have not been afflicted with the same issue.
Thankfully, there are a couple of relatively easy workarounds. While the authentication prompt is invisible, it is still there, so people have been able to log into their apps as they normally would, although in this case they’re essentially putting a finger on the Home button and hoping to get lucky instead of responding to a deliberate prompt. Shaking the phone also seems to be effective, jarring something loose and making the dialogue request materialize.
Of course, it severely limits the utility of the iPhone if users are unable to log into apps, so Apple will likely try to introduce a fix as soon as possible. Apple phased out Touch ID in favor of Face ID on recent versions of the iPhone, although several rumors have suggested that Touch ID could make a comeback through the introduction of in-display fingerprint biometrics.
Source: 9 to 5 Mac