This is the second confirmed totally made up character to allow "diversity" in the TV show. Here is a discussion I found on this character.
"Ella-Rae‘s involvement in Netflix’s The Witcher was first revealed after Henry Cavill and the rest of the team presented the first teaser to the world at San Diego Comic Con. Her role has been a complete mystery ever since. We’ve reached out to Netflix and can now exclusively confirm who her character is.
Ella Rae-Smith plays a character named Fola. She is most likely an original addition to the show created by showrunner Lauren S. Hissrich and the team."
And it has been confirmed by the executive producer that some major changes to the books were made right from the very start.
"The Executive Producer insists that fans should not worry, and promises clarity will come as the season unfolds. “After the first episode, many viewers will think ‘that didn’t happen in the books’ or ‘that’s not how this scene went’. They will ask ‘why was it done this way?"
The other diversity character is Fringella's uncle, Artorius Vigo. While this is at least a real character in the books/games they changed his race.
Which BTW brings up if they will still have a relationship between Geralt and Fringilla.
I support real LGBT rights (Liberty, Guns, Bible, Trump)!
No collusion, no obstruction = 2020 VICTORY.