How to improve shadow quality on passthrough?

We can now have shadow on passthrough thanks to the PassthroughRelighting example in the MRUK, however, the shadow casted on the room mesh is very pixelated. I have tried to increase the shadow quality, resolution, adjust the bias etc but nothing seems to make any changes to the pixelated shadow. 

Does anyone know what can be done to improve the shadow quality on passthrough? 

Thanks!