I follow the seen around LG G3 d855, G4 h815 and G5 h850.
On the LG website LG H815(LGH815) aka LG G4 the last officially available StockROM | firmware is offered with Android 6.0.x Marshmallow.
On this website an [Official] Android Nougat 7.0 On LG G4 H815 (LG-H815_Official_v29A.zip for the LG G4, by Kessaras) is offered. The zip-file has a size of 2.210.343 KB (!)
I to think something fishy is going on! How do you judge this matter?