Chess960 castling bug

Hey,
Please check this game: lichess.org/jKSuxM8BEq5Z

On move 18, black should not have been able to castle because the d8 square in under attack. If I remember correctly, one cannot castle if the final rook/king squares are under attack. Isn't that so?

Thanks

You may not castle *through* or *in* check so that only applies to the king - the rook is not subject to such rules and may be under attack.

You are only not allowed to castle if the king squares are under attack. You can castle if the squares of the rook are under attack (before or after castling).

In standard chess you can't move the rook to a square that is attacked because that is always the square the king passes through and the king cannot pass through check.

In chess960 that doesn't always apply, as in the above position, and therefore it is legal.

Thanks. Weird rule.