New Message Icon Not Disappearing in Open Threads

Description:

There is an issue with the new message icon on open threads: it does not disappear after a new message has been received. This requires users to manually close and reopen the thread for the icon to disappear, which is particularly inconvenient for those with a large number of active threads. It is leading to confusion amongst users.

Steps to reproduce:

1. Open an active thread.
2. Receive a new message in this thread.
3. Notice that the new message icon does not disappear.

Expected behavior:

The new message icon should disappear after receiving and viewing a new message in an open thread.

Actual behavior:

The new message icon does not disappear until the thread is manually closed and reopened by the user.

Screenshot

Server Setup Information:

• Version of Rocket.Chat Server: 6.4.6
• Operating System: Linux
• Deployment Method: Docker

Client Setup Information

• Desktop App or Browser Version: Rocket.Chat Electron 3.9.9
• Operating System: Windows 10

Additional context

Relevant logs:

The issue names no source files or tests. Reproduce the behavior in an open thread, then trace the frontend state for the new-message icon after a message is viewed. Done means the icon disappears without closing and reopening the thread, with a regression test added if the relevant test area is found.