What is the ruling on a female سؤال (inquirer) working in a salon that does the forbidden practice of hair extensions, given her dire need for work and her fear of being fired?

Your work in this place is permissible under Islamic law, as long as you do not directly engage in forbidden acts or assist in them. If you are asked to perform forbidden acts, such as plucking eyebrows (namṣ) or hair extensions (waṣl al-shaʿr), it is not permissible to comply, and you must clarify the religious ruling to them. Nevertheless, seek another job far from doubts, for whoever fears Allah, He will make for him a way out and provide for him from where he does not expect.