As of now, apparently it makes no difference to your acceptance if you are vaccinated or not. However, if you are vaccinated and you say you are not, then technically you would be lying on the application, which there seems to be no reason to do that. Uploading the covid vaccination card is just as easy as uploading your covid test, so no reason not to upload it. My wild a$$ guess is that they want it for record keeping purposes and to see what percentage of current visitors are vaccinated. PERHAPS, just perhaps, if they see that the vast majority of people are vaccinated, it will cause them to go to requiring ONLY proof of vaccination sooner?? One can hope.