Sound more like voluntold than voluntary to me.
New EU agency planned
In the risk analysis, providers must check whether their services can be misused for the dissemination of abuse material or for contacting children. There are to be three categories for this: high, medium, and low risk. Providers in the highest category could be obliged to participate in the development of risk mitigation technologies.
Counterpoint:
Reality Check: EU Council Chat Control Vote is Not a Retreat, But a Green Light for Indiscriminate Mass Surveillance and the End of Right to Communicate Anonymously