From what Airbnb says the single-fee setup is mandatory for certain hosts, including most hosts using property management or channel management software, plus some country/category cases, while the split-fee model still exists for many others. Airbnb also says some hosts who dont use management software will be transitioned over time, which is probably why the email sounded broad. So it’s not automatically everyone right now, but it’s also not just channel-manager hosts forever. Best move is to check the exact fee model shown in your account/listing pricing settings, because Airbnb is rolling this out in phases