just type

"mat_specular 1" in the console

to the console
or delete "mat_specular 0" line
from your autoexec script

C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod\cfg

(edit it with notepad or whatever)

then find autoexec.cfg,

this doesnt break your gmod btw
its just a script that makes a command you putted in execute when you start playing gmod
for example

if you put in a console command (like mat_specular 0, your enemy in this disscusion,) it wil execute when you start playing

so whats the fix?

DONT HAVE MAT_SPECULAR 0

also mat_specular 0, fixes almost every reflextion that is a missing texture, so how may i fix this, you may ask?

i dont think there is a fix for that, but it may be fixed with a addon, but i dont know that, so please dont have mat_specular 0

please tell me if this worked 😃