The whole line looks rare and unpromising for white. The only way 9...f5 could be weakening is if 10 pxp worked but 10 ...pxp gives black a huge centre. Otherwise it is shutting any kingside chances for white down, and black can castle kingside.
9....f5 doesn't look the only way black can play it, possibly Ng6 too but then Bd3 might give white chances if black castles kingside.
Recently, I bought on chessable the course Lifetime Repertoires: Giri's French Defense.
I have a question about a line in the advanced variation.
The line is:
1. e4 e6
2. d4 d5
3. e5 c5
4. Nf3 Nc6
5. Bd3 cxd4
6. O-O Bc5
7. Nbd2 Nge7
8. Nb3 Bb6
9. Bf4 f5
At move 9, it is not really clear to me why to push the f pawn two forwards and I would like to know the reason. Because I would think it would weaken the king side. Also, after move 9, Anish Giri draws arrows from c8 (where the light-squared bishop is currently located) to d7 to e8 (where the king is currently located ) to h5. Where should I move my king to make this path clear for the light-squared bishop? Castling queenside does not look like a good option to me, because I don't have a pawn on the c-file.