G4 right away is not a terrible move. I didn't give stockfish a ton of time, but it was either the second or third choice. After ne5, however, g4 wins a pawn. Stockfish doesn't actually think that keeping the pawn is the best choice, but bxb7, rb8, bxa6, rxb2 is viable and good for a nice pawn up advantage. But the bigger issues are that white's pieces just really come alive if white gives the pawn back. Bxb7, rb8, bd5 (not keeping the pawn) rxb2, e4 and bf4 is coming. The black cpawn is going to be a pita to defend if its even possible, and the black light squared bishop is stuck out of the action.
Question regarding a position from Roberto Molina vs Alessia Santeramo
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How come that in this position the engine dislikes 1. g4 for white, going from a slight edge to an even evaluation, but after 1.Bd2 Ne5, 2. g4 becomes the main move for white and the eval shoots to +1.5~? I get that it prevents the loss of a piece and attacks the b7 pawn after the exchange of knights, but it seems like I'm missing a positional detail- otherwise wouldn't it be a decent choice for the previous move as well? how come it's okay to advance the pawns protecting your king with these new details?