If you're talking about Element switching its contributions to Synapse from Apache to AGPL, the rationale is that folks who want to commercialise Synapse will either have to a) opensource their changes, b) pay for an AGPL exception from Element, c) use a different server (e.g. Apache-licensed Conduit from https://conduit.rs) or d) write their own server.
This hardly feels like suffocating competition.