In Germany (i.e. for German accounts), select TV show seasons may be available as separate store items for language support. If you buy the German dubbed edition, then original language is not available. If you buy the original language editions, then German is not available. They are separate items to purchase. The may also be an additional edition with subtitles.
If you accidentally purchases the unwanted edition, then contact the iTunes Store staff to rectify that. They should be able to undo the unintended purchase and guide you to the correct one.
You may recognize the various editions by their details, such as Staffel vs Season vs Season (subtitled), and the language of the description. The editions may appear as copies with very similar cover art.
If the Apple TV app doesn’t show you these 23 items for this show, then consider making this purchase through the iTunes Store app on iPhone or iPad, if you have that.