This has been going on for years, including inside the EU, for those wondering. You can test to see if it happens for you by going to a flight website, getting a price for a flight, then go back a few times to search for the same flight.
The question of what you do to fight it is by clearing the cookie for the website, using a different browser and/or changing your location/block tracking (use a VPN or tor). Usually clearing the cookie is enough.