Per Section R303.4 of the 2017, 2020, and 2023 Florida Residential Code, whole-house mechanical ventilation is required  when the dwelling unit air leakage rate is less than 3 ACH50*:

R303.4 Mechanical ventilation.

Where the air infiltration rate of a dwelling unit is less than 3.00 air changes per hour where tested with a blower door at a pressure of 0.2 inch w.c. (50 Pa) in accordance with Section R402.4.1.2 of the Florida Building Code, Energy Conservation, the dwelling unit shall be provided with whole-house mechanical ventilation in accordance with Section M1507.3 .

Parallel language was added to Section R402.4.1.2 of the 2023 Florida Energy Code as a further clarification:   

R402.4.1.2 Testing.

The building or dwelling unit shall be tested and verified as having an air leakage rate not exceeding seven air changes per hour in Climate Zones 1 and 2, and three air changes per hour in Climate Zones 3 through 8. Dwelling units with an air leakage rate less than three air changes per hour shall be provided with whole-house mechanical ventilation in accordance with Section R403.6.1 of this code and Section M1507.3 of the Florida Building Code, Residential. Testing shall be conducted in accordance with ANSI/RESNET/ICC 380 and reported at a pressure of 0.2 inch w.g. (50 pascals)...

* 3 ACH50 whole-house mechanical ventilation "trigger" required by 2016 Florida legislation.