I am not sure where the process is for the AP E2EE extension.
I just wanted to share this as I know MLS was on the table but there are shortcomings in a federated environment.
DeCAF protocol which seems best suited to address the shortcomings DeCAF: Decentralizable Continuous Group Key Agreement with Fast Healing
Matrix.orgs draft decentralised.org · decentralised2 · matrix-org / mls-ts · GitLab