MrSnrhms, a developer for Spirit Realm Games, gave Motherboard temporary access to the team's iOS developer account, which showed that Apple did indeed reject the app because it contains Pepe, a cartoon frog that has been increasingly associated with the alt-right.
The description, for instance, contains the following poem: On r/The_Donald, MrSnrhms said that the game "combin[es] shitposting with autistic screeching" and that "Apple is full of cucks." In the game itself, you collect "tendies," a 4chan meme that has been widely adopted on r/The_Donald.
There are no apps in the App Store with Pepe in the title, and it does not appear in many meme apps and iMessage sticker packs (there are no Pepes in "MemeStickers," for instance).
"Apple has a higher barrier of entry to their store with their higher publishing fees and more strenuous review process," Jonathan Robins, the developer of Pepe Snap told us.
I even still have plans to update it again soon with more features." It's possible that Apple chose to reject Pepe Scream and other apps featuring the frog on the grounds that it could be considered a hate symbol.