Storm of Ink and Blood by Nisha J. Tuli

Dark magic courses through Zarya’s veins—magic that could save countless lives… or doom her world.
Shattered by Rabin’s betrayal, Zarya vows to leave all thoughts of him behind. In the dangerous city of Ishaan, she joins an ancient struggle for freedom.
Ishaan is a city of violent contrasts. Nobles and scholars live in golden luxury. But thousands of vanshaj workers are born into magical slavery—in punishment for a crime forgotten centuries ago.
Zarya is outraged, and certain that the fate of the vanshaj is linked to her own forbidden magic. She joins a band of rebels battling for their freedom, and with Yasen at her side she throws herself into the fight.
On a deadly raid, Zarya uncovers the key to freeing the vanshaj for ever. But to use it, she must harness a power that could tear her apart.
Only one person can give Zarya the strength to reach her destiny. The one who ignited her magic. Who brings her more pleasure and more pain than any other. The last person she wants to see right now. Rabin.