How does the restaurant want diners to present and prove their negative covid results?

Either a negative test or vaccine card

Just a pic of your Vax card.

Have to have a negative antigen or pcr test in the last 72 hrs. You can show them the results electronically.

You have to have your Vax card and show it to the hostess. I cannot remember if you can show your test results because I used my Vax card.