Apple has extremely/problematically vague guidelines about what constitutes spammy apps.

https://developer.apple.com/app-store/review/guidelines/#des...

> Don’t submit apps that are indistinguishable from what's already widely available. Opportunistically creating variants of existing app categories or popular apps degrades App Store discovery, reduces overall app quality, and harms both users and developers. Certain kinds of apps, such as dating, flashlight, sound effects, wallpaper, simple timers, and fortune telling, are well established on the App Store and we will not accept new submissions unless they offer a meaningfully different or improved experience.