Hi,
I have been aware of this issue in source games, It happens in left 4 dead 2 on very rare occasions and portal. But for half life 2 it is really dreadful. The first half of the game worked fine but in the second half now there are constant bright light that covers every texture/sky becomes overexposed and flickers depending on where you point the camera. The only way to fix this is to keep your flashlight on. I have searched online for it and have seen no other posts regarding it, besides an odd mention in a bug report 4 years ago. Was wondering if anyone found a solution? BTW it does not matter what effects I use, even just tonemap with nothing changed causes it.
screenshots
imgur.com/a/oRAADFS
(no reshade, no flashlight)
imgur.com/a/AZJ6Y0c
(reshade on, just tonemap with default settings, no flashlight)
imgur.com/a/Nihll9w
(reshade on, with flashlight)