According to the Embassy in Athens, Greece no longer has testing requirements to enter the country.
https://gr.usembassy.gov/covid-19-information/
Entry Restrictions to Greece Relaxed: As of May 1, 2022, travelers entering Greece are no longer required to display a certificate of vaccination or recovery from COVID-19, or evidence of a negative test result from SARS-CoV-2 infection.
So Princess needs to get with the program and update.