Whatsapp released stickers in last month’s update. This feature allows the user to send stickers to a friend, group and colleagues for interesting communication. Since then the App store and Play store got flooded with third-party apps, which provide different types of stickers and also let users make custom stickers.
But Apple is deleting these apps because they provide similar feature and also these apps have a dependency on other apps which violate Apple’s guideline. As Apple doesn’t want lots of apps to do the same thing.