Despite Tissaia's clear fondness for Yennefer, by the end of The Witcher season 2, she wanted both her and Ciri dead. Although Tissaia has always been very politically motivated, The Witcher season 2 made sure to emphasize those skills as she spent much of her time carefully influencing the council and doing her best to maintain a semblance of peace and order in the world. That goal was threatened by news that Ciri was still alive after the attack on Cintra.
After the first season, which focused on Geralt's journey reuniting with his Child Surprise, Ciri, The Witcher season 2 highlighted how difficult it would be to keep her safe. When Triss visited the witchers at Kaer Morhen to help Ciri control her magic, she learned that Ciri was a child of Elder Blood and had the power to fulfill an ancient prophecy. This prophecy claimed that Ciri would have the power to either save or destroy the world, which her many enemies were eager to exploit. Triss confided this information to Tissaia with the promise that she wouldn't share it with anyone else, but her silence didn't last long.
Related: What Elder Blood Means In The Witcher: Ciri's Magic & Source Explained
The potential for destruction that Ciri's existence posed in The Witcher led to the council's decision to place a bounty on her head. Tissaia initially wanted to honor Triss's wish to keep the news to herself, but when Vilgefortz learned the truth, he persuaded her that it was too dangerous not to act, and risk Ciri fulfilling the prophecy by destroying the world. During a meeting with the rest of the council at the end of episode 8, Tissaia voiced worries that Sigismund Dijkstra had known about Ciri's existence all along and planned to marry her off to King Vizimir,
Read more on screenrant.com