Hello, there! thank you for your patience. I was tweaking Half-Life 2 configuration files and found that the models ingame (the npc ones) had a very ugly light effect. They looked like plastic or something very shiny when exposed to lights. What I did to fix this particular issue was setting mat_dxlevel to 0.
I'm guessing your messing around with the configuration files caused the game to disable use of phongmask textures, which would lead to this effect since every phongmask-using model would then be using 100% phong instead
maybe try to see if you can manually cap their phong amount to a visually acceptable level