This is a very bad idea for many reasons.
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This idea gives the government the means to choose which groups they favor for participation in travel commerce based on whatever arbitrary set of metrics they can make sound half-reasonable. It is a huge amount of freedom to cede to the government and it will certainly be abused by bad faith government types around the world.
None of these things are new. These kind of passports are just electronic versions so you don't have to take with you papers.
Many countries already have these restrictions on travel today. It is just easier to show your smartphone than dragging with you papers showing you have been vaccinated.
It is like an electronic driver license, except for vaccines.