There are hints of “She’s/I’m not like other girls” throughout the whole book, the first time I noticed it was very early on, near the end of chapter 4 here:

"You are over scrupulous, surely. I dare say Mr. Bingley will be very glad to see you; and I will send a few lines by you to assure him of my hearty consent to his marrying whichever he chooses of the girls; though I must throw in a good word for my little Lizzy."

"I desire you will do no such thing. Lizzy is not a bit better than the others; and I am sure she is not half so handsome as Jane, nor half so good-humoured as Lydia. But you are always giving her the preference."

“They have none of them much to rec- ommend them,” replied he: "they are all silly and ignorant like other girls; but Lizzy has something more of quickness than her sisters."

It’s literally right there. I remember this well because I posted it on my instagram to point it out and talk about it with my friends.