I found some invisible textures. and that happens only when any mod is activated, when i disable all mods, textures are there, but when i activate a single mod, some textures go invisible
i also noticed in console that code guard has been activated (same as invisible textures, it activates only when any of the mods is running)

EDIT:
One mod actually works properly: BFE Enhanced
no invisible texture or code guard


tried other mods with this mod active and inactive.
then unsubscribing the mod.
nothing, the invisible texture and code guard are still there

EDIT 2:
OK, it doesn't happen in every mod
I just thought so because last two mods i downloaded did the same thing

from what i found it happens only with:
SS3 - Unity Edition
and
Serious Box Solid: campaign additions