However strange and counter-intuitive it might seem, the book move after 4.g4 is 4...Be7. The bishop will be trapped behind the pawns like in the French defense, but White has considerably weakened his kingside by g4. Keeeping the bishop on the kingside allows White to chase it.
If you want to play 4...Bg6 (?) then 5...h5 instead of ...h6 is an improvement compared to your line, but Black is still in trouble.
Even knowing this, that line (g4) is IMO the most dangerous in the advance variation, and has made countless victims.
Helo. I realy don't know if u faced that before .. but it's as kind of annoying line and may be called a gambit that white can force it once u pull out ur LS bishop in the advance variation.
I need your opinions about it . personally after playing this as black about 4-5 times .. i find it really advantageous for white.