Duration of protection against COVID-19 is currently unknown

Yes the FDA and Pfizer-BioNTech openly admit duration of protection is unknown

Straight from the FDA and the Vaccine Insert Sheet;

WHAT ARE THE BENEFITS OF COMIRNATY (COVID-19 VACCINE, mRNA) AND THE PFIZER-BIONTECH COVID-19 VACCINE?

The vaccine has been shown to prevent COVID-19 following 2 doses given 3 weeks

apart. The duration of protection against COVID-19 is currently unknown.

https://www.fda.gov/media/144414/download/