Not all conflicts around Christmas are about that obvious. The racist comment that is expressed without anyone standing up.
There is also a lot below the surface, I think. Such within a family that has felt to those involved during the year, but may not have been said high. Things that tend to run over if the mood becomes too pressured and the requirements for hard.
Because it may be during Christmas and other holidays as children who have it tough otherwise often get tougher. Things escalate and it also disappears for them safe (which can be school) for a period.
The problem does not appear due Christmas, but maybe they will be more visible to others then.
The only thing I really want to say is: Do you see or notice something that doesn't feel good - tell us. Ask, do everything you can. It's always worth it.