Hmm GSX might NOT be the problem, it worked perfectly before your MAJOR update
Why you keep repeating this ? Is there's something in my previous explanation which is not clear ? You are confusing cause and effect here.
The *cause* is some kind of installation problem or settings problem, or a problem with shaders, and the *effect* is that GSX is affected BY it, it's not CAUSING it.
The update has added PBR and, if your simulator is not installed correctly, PBR won't work and no, it's not something that happens just with GSX, it happens with several 3rd party airplanes that also use PBR and, for example, something that seems confirmed, is that if you update P3D with the Client only, PBR might not work correctly, so you'll have to use the Content installer to, or possibly reinstall the whole sim using the Full installer.
Again, nothing to do with GSX, which doesn't have any fault other than having exposed a problem you already had, but no add-on (including the previous GSX, which didn't use PBR) that requires the features that are currently broken in your installation, so your are being mislead "it must be the update", when it's not.