This bug isn’t specific to the PTR but it’s more likely the devs will see it here and I think it’s probably something that can easily be fixed.
0 Light Radius vs +8 Light Radius makes a huge visibility difference in original D2 graphics while it’s almost impossible to tell the difference in D2R graphics (you can easily compare by opening the images in new tabs and switching between them). Negative Light Radius seems to be working as intended.
Here’s my brightness settings for reference:
While I do greatly appreciate that the devs kept the same dark atmosphere it would be nice if Light Radius were as meaningful in D2R graphics as it is in original D2 graphics.