Unable to pruchase Plants vs Zombies GOTY

I have noticed recently that I can't purchase Plants vs Zombies GOTY on Steam. I have the suspicion that this game hadn't been properly marked and thus is hidden for people in Germany. SteamDB also doesn't indicate a region lock for Germany. After asking on social media like Reddit and scouring the Steam discussions, I can rule out that this is an issue on my end.

I just want to own PvZ GOTY on Steam and I'd love to see it back in the store.