According to Osho, disciples near a master may look very serious—not as a rule, but as a balancing to a nonserious master—and true relaxation shows up differently in each person: some laugh, some become solemn. Stop worrying about others; that urge to manage is ego. If another’s seriousness bothers you, it mirrors your own conditioning. Attend to your own naturalness.
Some people near a teacher will be serious and others playful; both are fine—don’t judge them, just be yourself and focus on your growth.