It's not a bug, it's a feature.
I was bored and made the tutorial and in the tutorial they say to kill crawling soldiers because they give LoS to the enemy.
You can try the tutorial and see yourself if you want.
This is not what this topic is about. It is well known that wounded soldiers provide LOS. However, there is a bug where they will provide line of sight
throughout the entire game. These soldiers have already stopped moving and can no longer be targeted, but their models remain on the field and provide LOS because they are bugged.