For avoidance of doubt, as not everyone will have read the “User control” section of the change proposal: the system is opt-out for everyone who sees the Privacy page in gnome-initial-setup, which is mandatory when installing Fedora Workstation. There you have to flip the switch to off or else data will be sent to Fedora. This switch is pretty prominent at the top of the dedicated Privacy page and it’s one click to disable, so I don’t think it’s a “dark pattern.” If you don’t like telemetry, just flip the switch and we’ll never collect anything (not even a report saying you flipped the switch, which is a bit of a shame, because it sure would be nice to know how many users disable the telemetry, like Ubuntu does).
Users will always be presented with this choice before any data is sent. E.g. if you are upgrading from a previous version of Fedora, then you don’t see gnome-initial-setup, and the system is opt-in, because we must not collect anything without user consent. To enable, you’d need to navigate to the Privacy page in gnome-control-center and flip the switch from off to on.
Fedora Legal says the switch has to be off by default if we collect any personal data. Therefore, we MUST NOT collect any personal data.