The OP might confuse this with the current PCR test exemption for fully vaccinated passengers on traveling to Dubai on flights from:
France, Germany, Switzerland, Spain when the passengers got vaccinated in those countries or the UAE.

That means a PCR test would be required for a passenger who got vaccinated in Portugal, no matter that the vaccination status itself would not be different from a person vaccinated in any other country with an approved vaccine.

I don't know why they picked those countries only, but I can confirm from experience that this is how it works and that this is being checked at the airport of departure and in transit in CDG.