Unread count is showing the wrong count
Android does not provide a way for apps to declare how many unread messages they have. Action Launcher does the best it can by attempting to extract unread counts from notifications, but these values can be unreliable. Given Android’s limitations in this area, there’s unfortunately there’s little that can be done here. It’s just not possible to always get an accurate unread count on Android as it is on iOS.
In Android Oreo, Google introduced the concept of notification dots, which moves away from a count and instead embraces a single dot to let you know there’s a notification. You may wish to consider using this method, as while it is more limited, it is also more reliable.