Connection to weak partner nodes

I am pairing a smart plug in the same room whre my conbee2 is placed.
Why it is connecting to one of my weakest devices (gu10 light on the first floor) and not with the coordinator or building routes to one of my hue lights in the same room or neighbor room?

All devices are routers ? So need to have more than 1 connexion ?

All devices which are near to power plug are routers. Now, the routes were build to other devices and the coordinator. Took some time.
But I don’t understand why the first route was build to a device which had a much worse connection compared to other devices which were near by. What’s the logic behind?

I don’t know the mesh algorytm, but for me taking the better way is only used for end device, as router support more connexion, the network use the maximum it can use.