You're right, thanks for pointing this out. It's probably an issue with the routing software. Osmand has trouble plotting a pedestrian route, as does Valhalla:

https://www.openstreetmap.org/directions?engine=fossgis_valhalla_foot&route=51.51713%2C-0.12533%3B51.51562%2C-0.12661#map=19/51.51648/-0.12599