The shadow map generation for directional lights is too aggressive when culling potential shadow casters.
I have built a room with vertical blinds along a window-wall facing the sunset. When the blinds are closed, everything works okay most of the time, until I get close to the far wall.
At certain angles and positions, I can see that the engine is incorrectly culling certain slats of the blinds, leading to bright vertical bars at the edges of the screen:
I don’t know if this is because of the softening of shadows away from the caster, but it would be useful to have some way of adjusting the aggression of the culling to get rid of these light-leaks.
EDIT: It’s definitely something to do with the angular diameter of the Shape settings. Reducing that from 2.5 to 1 ‘solved’ the problem.