What about my mental health history?
Depression, narcissistic personality disorder, bipolar diorder, addictive personality?
What about my adherence to religion? How strict am I?
I'm stretching a bit admittedly, but i'm trying to make the point that all of those things have resulted in many, many deaths over time.
As i've already said, in isolation and on the face of it, proving you have been vaccinated against covid is probably a good idea, but you simply cannot be ignorant of the fact that there is potential for abuse in future by unscrupulous people or groups of the precendent set by having to pubicly declare your medical history.