If I recall correctly, Wights, being Light Sensitive, did have disadvantage on attacks while being exposed to a light source. At least regular Wights of Bone Keep in game version 2.6.0. But now in 3.3.0 a Wigth in a random encounter and that special named Wigth outside of Bone Keep both didn't have disadvantage.
An exposed to light Wight attacking without disadvantageThe tooltip seems like it's meant to be of a certain kind of Soraks, so either those Wights learned it from friends, or it's a bug.
Light Sensitive tooltip saying it's a SorakP.S.: the log on the last pic says the Wight attacks with disadvantage - that's because of Faolan being under Protection from Good and Evil spell, not because of Light Sensitivity.
Another weird thing on the last pic is that the rightmost Skeleton Archer wasn't a part of this encounter. From the two on the initiative tracker, one stands on a block near a loot bag and the other is on the left, beyond current camera scope. As soon as this encounter ends, another (actually, third) encounter starts, against that single Skeleton Archer.