Unlike the chudidar where the cloth is constricted at the knee and the salwar which is constricted at the ankle, flared trousers were also worn with the kameez. The kameez initially was a tunic with skirt but later you can see shorter, simplified versions. Given the pictures here, the fashion appears to date back to the early 19th century (strictly more Lucknowi than Mughal). The sharara is also an example of this, though it may sometimes be constricted at the knee and then flare.
The paintings are all of nautch girls so it’s a little difficult to say whether the same fashion was followed by other women. However at least one of the links is to the costume of the Queen of Oudh so it seems like it was the prevailing style.