The route view indicates they are all direct path from hub (C8) which is most certainly not how they physically are laid out. 3500 sqft house, concrete walls. Was expecting relay like Zwave.
What type of devices are all of these? Not all Zigbee devices are repeaters. According to your graph, it appears that none of your devices are repeaters. Repeaters appear as blue. This is why all of your devices are directly connected to your hub.
As I mentioned, they are all new ZigBee 3 Zemismart/Tuya switches.
MOES ZigBee Smart Touch Wall Light Switch,Requires Tuya ZigBee Hub,No Neutral Wire/N+L Wiring,No Capacitor,Smart Life Tuya 2/3 Way Remote Control, Work with Alexa Google Home, 2MQTT,1 Gang White https://a.co/d/fVASdta
The graph's derived from limited info, mainly what shows up in the hub's getChildandRouteInfo child & neighbor tables and cache of recent route discovery requests-- it doesn't take into account the perspective of all routers, which maintain similar info.
So the resulting picture (not always an actual map, unless the mesh is very simple) only accounts for the following:
The hub's neighbor routers (repeaters within a 1 hop radius of the hub). Neighbor relationships among other routers 'deeper' in the mesh may not be shown correctly.
Devices which have been (or are currently-- since current connections are combined with historical ones) reachable using a neighbor router as the first hop in the route, limited to recent route discovery requests that have appeared in (transient) route table entries-- NOT the internal routing table.
End devices for which the hub is the parent device (child devices of other routers may be erroneously depicted as their parent if they are the first hop in a route to that child device, and intermediate routers may not be shown at all)