gemfx is a shader tweaker....i use ReShade and is very good for tweak and increase the gameplay ambience, BUT things as the nebula resolutions doesn't benefit from this....let's try to not mix arguments...this is a serious nebula rendering problem, nothing that a shader enancher can fix....let's stay on topic please.
Regarding that screenshot, well at least it seems that problems are still here and aren't been solved yet.
I tried to tweak the graphicconfiguration.xml file increasing high resolution nebulas up to 3, since the orion nebula is pretty full, but no luck....in game nebulae are always low rez, in the galaxy map them are rendered correctly.
Then if thats the case I think it should be reported as a bug