Hello,
Please open Aqua Mail settings -> message notifications -> enable “Smart Watch enhancements”.
This also changes how on-phone notifications look. You’ll be able to expand (swipe down) on a notification that’s “about” more than one message, turning into individual “cards”, one per message, each with its own action buttons (mark read and so on).
This “enhanced” notification style – which first appeared in Android 7.0 – works with the new Samsung badge feature as expected, even when there are multiple unread messages.
PS – the badge count will clear when the app’s notifications are cleared.
Please let me know if we can assist further.