I took delivery of my Plus Four auto on September 1st 2021 and have not had any radiator problems so far. I am told that when it goes in for the brake recall it will also have a swirl pot fitted. Apparently this is the case for all cars.
Snap. I too took delivery of a Plus Four auto on 1st Sep 2021 and have had no brake or rad problems. Now had the recall done, so fingers crossed.