Scarcely Lethal Noob
It appears that if you wear the Nose Candy (Horrific) Style with the !wear command or !item command. The cosmetic has some weird and buggy white textures moving around the head of the pyro but if you have the cosmetic and wear it this doesn't happen.

I believe this cosmetic has an issue on the server's side? Can this be fix?

Using the !wear command

Having the cosmetic on your inventory and wearing it