In "The Witcher" book series written by Andrzej Sapkowski, Falka is a character from the past, and her story is intertwined with Ciri's lineage and the prophecy of the Elder Blood. However, the books and the TV series might take different creative directions, and any information about Season 3 would be.
To learn about Falka's blood origin and her interactions with Ciri in "The Witcher" Season 3, I recommend checking official sources, such as watching the show or reading any new materials released by the creators or the author .