Same reason why we call London “Londres”, and why the English call Roma “Rome”. Changing city names depending on the language is a pretty common thing yet everyone seems to only notice it in Porto 😂
A very common mistake is to lock yourself in your reality (universe, language, beliefs). If you had taken the slightest trouble to see how to say and write the name of this place in Portugal, you would know the reason why we Spanish speakers call it Oporto . Open your mind !
