This is not a single road as shown on the map, but two separate roads which terminate at the map marker location. There is a residence inbetween that blocks the two roads.

This link has negative consequences for routing - access to Abeyratne Mawatha is easier through this (nonexistent) through road, so OSM based routing products tend to recommend it, while in reality no such throughfare exists.

There is an unpaved track which runs parallel to Ambillawatte Road for about 70-80 metres and then does a 90 degree turn to run parallel to 20th Lane, starting from the map marker.
This track is visible on satellite view, and has 10-15 vehicles traveling on a daily basis - from the residences at the end of the track, and also from a welding and grill work business.

This used to be on OSM at one point, but was removed. Access from the residences/businesses to the main road is via Pirivena Road