Why were mercenaries banned?

Mercenaries were banned primarily due to concerns over their loyalty, accountability, and the potential for abuses in warfare. Their involvement in conflicts often led to a disregard for international humanitarian laws, as they were not bound by the same Codes of Conduct as regular military forces. Additionally, the use of mercenaries could undermine state sovereignty and lead to destabilization in conflict regions. Various international treaties and conventions, such as the UN Mercenary Convention, have sought to restrict their use in armed conflicts.