While doing the phantasm ship UQ, I saw someone with an interesting set of mech wings (The player in red that is in front of me), I'm wondering what they are and where they came from:

Looks like Stabilizer B from the current FUN Scratch. It is rotated and adjusted significantly considering that its default position is as a rear skirt.

Also, remember that you can check someone's Fashion details from the Nearby Character menu.

If on PC you can also push T and click on the person directly

Thanks for the tips