According to the Nightmare Before Christmas Part 2 Holiday event, Christmas doesn't exist in Twisted Wonderland.
There was an old and forgotten holiday called Day of Desire based on Swing the character based on Oogie Boogie who was a trouble and chaos making fae.
I wonder if some of the Jujutsu Kaisen girls ever told or teased YN about the mistletoe kiss tradition, and if she remembered and what would have happened of she told Grim upon seeing one in their holiday shopping and the beast blurted it out to the love rival crazed guys.