Deleting conversation is not clearing notification counter on app icon

[ghost]

Describe the bug
After deleting a conversation without opening it while there is an unread message, the notification counter is not updated on that device.
I have read the new message in the chat I deleted on another device so I do not need to read the message again and (in this case) I do not want to keep the chat in the chats list.

To Reproduce
Receive a chat message (in this case, the message is a 2FA code from a bank)
Unread counter increases from 0 to 1 on original and 2nd device (next)
Read the message on a different device (Snikket on another iOS device in this case)
Unread counter on 2nd device changes to 0
Unread counter remains 1 on the original device (iPhone)
Delete the chat completely on original device
Unread counter remains 1
Force quit and reload Snikket for iOS
Unread counter remains 1
Locate contact entry for original sender, tap to open chat again
Scroll down to bottom of chat for force 'read'
Unread counter is now 0 on iPhone

** Extra issue **
If this alert comes from a source that is not in my contacts, there is no way for me to fix the problem until I get another message that re-opens the chat...

Screenshots
If applicable, add screenshots to help explain your problem.

Software versions:

• App Version: Version 1.2.1 (4)

• iOS version: 16.5.1

• iPhone model: iPhone Pro 13

• Server software: Snikket
  The message discussed in this bug report comes through jmp.chat from a bank using SMS 2FA. The server is self-hosted by jmp.chat.

Additional context
None

[halictuz]

I've kinda the same problem. Uninstall/re-install fixes it but it comes back later and I don't know how and why exactly. OPn iPhone X with latest iOS version.