It’s doing the same thing in Mautic 4.4.12, but only in the subject line. Emojis work fine in the message body.
For example, shows up as :tada: in the subject line. I tested it across several email clients, and they all accept emojis in subject lines without issues. Interestingly, the emoji even appears correctly in Mautic’s email channel subject line, but it gets converted back to text when the email is sent out. Even the example email preview shows text instead of emojis, so it seems something broke along the way.
I’m not sure which version introduced this issue since we don’t often use emojis in subject lines.