We need more details to assess your "case". Were you booked on 2 separate tickets (but bags checked through) and the European flight booked as a MiNi fare ? If yes, this is normal that you had to pay a baggage fee, as the MiNi fare includes no bag. If you were booked on a single itinerary, then this is not normal as I think the rules of the most significant sector apply to your entire itinerary, in your case the intercontinental sector.