Relationship with their peers or even personal relationships with significant others (problems, tensions, etc that can evolve in such relationships can cause significant stress).
Changes in their bodies can trigger them to be more self-conscious and it can be stressful to be the "odd" one in the group.
Thinking that everyone is watching you at all times so keeping very high expectations from oneself which can be stressful and also hurtful if expectations are not met.
Instability in family either due to financial conditions or divorce, abuse or many plethora of events.
COVI.D brought about many death so losing a loved one is high stress factor.
Many students also do not get adequate sleep because they are on their phones all the time (even past bed time) and lack of sleep can bring about many negative things one of which is stress.
I can go on and on. The list never stops honestly.
