The reason why the reflections are so intense with such low light is a problem with the Source engine, which does not calculate well through certain obstacles

Aaah! Finally, you are right, but it's not a texture problem. You see that light reflected on the floor?
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2807125999
The light come from this vent:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2807126087
If you remove the reflections, it will happen on all maps the same, and it will no longer look like shiny metal, but something similar to paper, like the vanilla game, and it is worse in most scenarios.

at the near of the elevator

I can't find that particular room, but there are a lot of metal pipes with reflections on that campaign, and in complete darkness they can't be seen, so cubemaps are fine. Can you tell me the approximate location, and the map?