I found a problem with the country flag displayed at the German website of Fairphone.
Unfortunately I (as a new user) can embed only one image in a posting, so I have to show both flags in one screen shot.
I think flag and abbreviation are for different purposes: The flag is for the country your reside in, the abbreviation for the language of your choice.
I can just speculate. When you visit the standard version of the shop (shop.fairphone.com), the Dutch flag is shown, too. Looks like a default setting.
Because that’s the home country of the fairphone, so I guess, it’s the default setting. The ‘.de’ then only sets the language.
But we are also just users here in the community, that’s a question for the Fairphone staff, if it’s bothering you that much: Kontakt - Fairphone
Also keep in mind that buyers of German language might buy from Austria, Belgium or Switzerland as well. In the latter case (Switzerland), the country setting gives you a very different price for the Fairphone (359€ for the FP3, 399€ for the FP3+, compared to 399/439 in the other countries).