When you have the following qml (also works with widgets, etc):
It will render all but the last emoji without colour and the last one with colour. Currently I have to surround all emojis with a font tag, that selects a colour emoji font, just so that I can have coloured emojis. I would appreciate it, if Qt would actually render these emojis as colour emojis, so that I don't need to use the RichText format. This probably happens because DejaVu Sans supports some of those emojis, but only in black and white.
https://bugreports.qt.io/browse/QTBUG-71929 seems to have also described this issue, but it was closed as a duplicate of a Windows bug, that was fixed with a Windows specific patch in 5.15. Since I can still reproduce this on Linux, this seems to still be an issue.