What happened to Sarah Bolger's Jade on Into the Badlands? The character disappeared after season 2 of the AMC series, but her absence can be explained by the direction of the story and the state of the cast in season 3.
Jade was part of a rather complicated family in season 1 of Sunny (Daniel Wu). Like many of the characters, Jade's life took a big turn in season 2. Jade married Ryder and took over Quinn's barony. Jade and Ryder ruled Quinn's land together.
Jade's final episode of the series came in season 2, episode 7, titled "Black Heart, White Mountain". Quinn returned to take back what he felt to be rightfully his, and made a temporary alliance with the Widow (Emily Beecham). Together, they led their forces into the Armadillo Territory. After storming her base, they managed to easily defeat Jade. Though it was initially decided that she would be put to death, Quinn declared that she would be taken to the border and banished forever. Some fans expected Jade to return with a vengeance, but Jade's exile was actually the end of her story on Into the Badlands, with no reason for her to come back.
Sarah Bolger is currently the female lead on the FX series and Sons of Anarchy spinoff, Mayans M.C, which began airing in the fall of 2018, only a few months after Into the Badlands season 3 premiered. Her new role could easily explain her departure from the series, but it's also likely that Bolger was never expected to return as Jade in the first place.
The Azra and the Gift, two things that weren't connected to Jade in any way. Also, most of the characters that she had interacted with -- except for Lydia -- were gone, so there wasn't a clear place for Jade to fit into the story.