Is it permissible for a woman to uncover her face at work if it is a fundamental requirement for the job and she faces difficulty finding another well-paying job, knowing that she usually wears the niqab and some scholars have differed regarding the ruling on covering the face?

A woman is not permitted to work in an environment that requires her to uncover her face in front of non-mahram men, because covering the face is a religious obligation when there is a concern of fitna (temptation/strife). If it is possible to perform the work inside an office without non-mahram men entering, then there is no harm, provided one is careful not to be lenient in uncovering the face in the future. Piety and reliance on Allah bring sustenance. "And whoever fears Allah – He will make for him a way out, and will provide for him from where he does not expect." (Quran 65:2-3). It is advisable to search for work from home, or for a righteous husband who might make work unnecessary.