Maybe if I had only bid 2♦ instead of 3♦ GIB may do better but there's really no reason for it to bid 4♠ here.
- 3♦ says 5+d, 4+s. Kind of feel like it should be 6+ d and 4 spades exactly.
- I don't think GIB should ever bid 4♠ on this auction with spade support. With GF and 4♠ it should just bid 3♠ IMO. 4♠ arguably should be a diamond splinter? And in any case with only 3 cd support and 6 hearts it should prioritize rebidding hearts over any number of spades.