[Bug]: System tray icon stays a permanent "unread"

[DominikMendel]

Describe the bug
The system tray icon for prospect mail always shows the red icon for unread.
When not signed in, there is no unread red icon.
Once signed in, it never goes away. Even with all mail read.

Is there a setting to alter this behavior?

To Reproduce
Steps to reproduce the behavior:

1. Sign into mail.
2. Have all mail read.
3. Observe system tray icon.

Expected behavior
System tray icon should remove the red dot when all mail is read.
Or apply some configuration setting to allow so.

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

Desktop (please complete the following information):

• OS: [e.g. Ubuntu 23.04]
  Ubuntu 22.04.4 LTS
  Snap version of prospect-mail

Additional context
Add any other context about the problem here.
Also, did you tried another build (AppImage, deb, rpm)?