Re: emoj test in topic title
As I recall, it's not the same as the support for those same emoji characters when used in the body of the post.
In the subject line, phpBB is fully depending on whatever support your web browser and device has for being able to display those emoji Unicode characters. As opposed to the message body, where phpBB is replacing those emoji Unicode characters with a consistent Twemoji-based image.
Which is why the subject line and the first line of this post may look different to you, even though they are exactly the same characters.