this idea more often seen with the black pieces via 1.d4 b6 2.bg5 bb7 3.e4!? bxe4 4.d5 where black must know a thing or two to prove a slight advantage but nothing more (may -0.5 advantage tops)
with a tempo down this is just plain bad. White should just play c3, nf3 e3 and simplify the center, and he is a clear pawn up. He shoudnt be afraid to trade away the fianchetto bishop if it simplifies any congestion in the center.
I’m guessing that it is due to black blocking the bishop from the long diagonal after 3. Bxe5 d4 but it seems like white would be winning after this.
Any ideas?