A provision of the Healthy Hunger Free Kids Act requires schools to establish a policy for unpaid meal charges (IOUs). Schools must notify families, in writing, at the start of each school year of their policy. These resources from USDA clarify this rule:
The Pennsylvania House and Senate have put forth anti-lunch shaming bills. As of this posting, it is expected that these will become law. The house and senate versions are nearly identical to each other. Read House Bill 1403 to familiarize yourself with what is proposed.