GM Level Gameplay from my side.
If your opponent had played 4. Qh4 to exploit your first mistake then it would've characterised the match. As it turned out it was a match of blunders and counter-blunders. You had the match won twice then threw it but so did your opponent so it came down to who made the last critical mistake. Hopefully it's obvious that GMs wouldn't have thrown the match like this.
If your opponent had played 4. Qh4 to exploit your first mistake then it would've characterised the match. As it turned out it was a match of blunders and counter-blunders.
After Qh4+ g6 the position isn’t any worse than before, no?
g6 is the correct defence but it's at the expense of a weakened pawn structure so Qh4 is still the correct way to exploit the mistake of advancing the f pawn early.
g6 is the correct defence but it's at the expense of a weakened pawn structure so Qh4 is still the correct way to exploit the mistake of advancing the f pawn early.
ehh idk if i’d consider f4 a mistake. it’s not the most accurate move but after f4 white has a stonewall-esque structure and white’s center looks really solid. f4 isn’t a top move, but stockfish doesn’t hate it.
At depth 20, f4 turns a +1.2 position into +0.5. There are similar losses at lower depths also. More generally though, advancing the f pawn so early is almost never a good idea. You're right that in this case White can sort of get away with it because they can still Castle after fending off the Check.

