It’s a phase they go through that is very common when adjusting to a new caregiver. The parents unfortunately made this much worse by switching providers. That has caused even more stress and heightened separation anxiety. Once he learns that he is in a safe space it will go away. It might come back if they go on vacation or something soon after he started but otherwise he should be ok. I would just reassure him in a calm voice and then ignore. It’s something that he has to go through, poor little guy
