According to the WGA website (i.e., https://www.wga.org/employers/agencies/agency-code-of-conduc...):
"The Code of Conduct is a landmark agreement that realigns agency incentives with their writer-clients and eliminates the conflicts of interest inherent in agencies’ receipt of packaging fees and financial interest in production entities. Agencies signed to the Code may only represent writers for a 10% commission and may not receive packaging fees or be affiliated with a company producing or distributing motion pictures.
The Code also contains important provisions on how agencies must represent writers, provide timely information to the WGA to enforce the collective bargaining agreement and writers’ individual agreements, and promote non-discrimination and inclusion."
If interested, here is the complete 15-page WGA Code of Conduct: https://www.wga.org/uploadedfiles/employers_agents/agencies/....