Not laziness. Not a phase. School refusal is when a child has intense anxiety or other strong emotional response to going to school, and tries to avoid it through physical symptoms, panic, or outright refusal.
"I don't want to go" happens. "I feel sick/have chest pain/can't breathe at the thought of school" is different. That's refusal.
It's often rooted in anxiety, depression, or a specific school issue (bullying, academic struggle, social anxiety). It's not something to "push through" or ignore. It needs professional attention.