If you cannot join the conversation just now, don't worry! You can now mute chats one by one
You can mute only those chats you don't want to receive notifications from, individually, without affecting other conversations. You will not be interrupted by these chats anymore until you unmute them.
You can mute both one-on-one chats and group chats. Here's how:
From a chat, tap the '⋯' symbol at the top-right corner.
Switch 'Mute Notifications' on.
Tap the '〈' symbol to go back to the chat.
To unmute a chat, follow the same steps but switch 'Mute Notifications' off.