Strange grid artifact when using point lights

Hello everyone,

there is a strange problem with my lighting on a particular zone of my game: whenever I play the level in editor or from a build, a strange light artifact similar to a grid appears. It doesn’t show in the level editor however and disappears if I press “eject” and change the light in the level.

Anyone has an idea as to why this is happening?

Here is the views from the level editor:

And here it is in game: