In the example the incoming road from the ne meets the outgoing road to the nw at the same node. This is not the correct way to map as incoming traffic should drive along a small segment of the roundabout before reaching the first node of the exit road.
Same happens an the western side of the junction. This is termed shortcutting the roundabout.roundabout.
See ‘Ways connecting to the roundabout’ on the wiki roundabout page
https://wiki.openstreetmap.org/wiki/Tag:junction%3Droundabout