Is it obligatory to leave work immediately, or is it permissible to remain in it temporarily while searching for another job, when the current work (as a translator in a dental clinic) contains a suspicion of being unlawful due to cosmetic dentistry performed without a therapeutic need?

If it becomes clear that a job is unlawful (haram), the basic principle is that it must be abandoned immediately, as repentance from all sins is an immediate obligation and it is not permissible to delay it. As long as a person has sufficient savings to cover their basic expenses, they are not compelled to engage in unlawful work.