[skeeks]

The official validation apps will not show this detail to the user. Unofficial apps may come up but app stores will probably quickly ban those (they are very careful about the whole COVID topic in the playstores). There is still the chance of sideloading the app, but one does also need to consider if the vaccination information must really be protected that hard. In most countries, it's more or less randomly when and with what kind of vaccine you got vaccinated. And the really important information in my opinion is: is someone vaccinated or not? And this information is what the bouncer needs to know to let you in...

[nomercy400]

Imagine Facebook sending any app that would have 'Login with Facebook' functionality, your full profile, including your plaintext password.

Would you trust every and all third-party applications with this 'Login with Facebook' functionality, to not look at your plaintext password? Or would you rather have Facebook not send your password in the first place?