Today I talked to customer support they said you should meet certain criteria for the promoted gig, (and my gig meets certain criteria) but they also said...
"If the criteria listed there are met, but your Gig is still shown as unqualified, this means that the criteria mentioned under “You meet additional quality metrics” aren't currently satisfied. These criteria are based on internal performance metrics and cannot be disclosed.
Please know that your performance is monitored on a daily basis, therefore, while your Gig may be unqualified today, this may change tomorrow. What you need to do now is to keep providing the best services possible."
What I understand is that it doesn't matter if you meet the standards or not. It is up to Fiverr to rank or de-rank your GIG whenever they want or turn off the promoted gig option and you have no choice.
that's simply mean reviews and rating does not matter.