To celebrate the arrival of 2023, Messenger released a “Happy New Year” chat theme that adds fireworks to a conversation’s background. When this theme is activated, the conversation’s emoji will automatically change to the party popper emoji. In addition, four word effects will be added to the conversation for the words “cheers,” “fireworks,” “midnight” and…

(SOURCE) https://www.adweek.com/media/messenger-how-to-use-the-happy-new-year-chat-theme/