From FIDE Law of Chess, article 3.8, it is stated as:
Now, coming to My game vs killin_pieces on lichess.org :
After move 9, situation was something like this: b1 was threatened by my opponent's light square bishop:
Still I was able to give him a discovered check on move no. 10.
which clearly contradicts FIDE Law of chess article 3.8.2.a, stated as :
Castling is prevented temporarily: if the square on which the king stands, or the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces
Can anyone please explain me how can this be possible ?