What is the ruling on working in a shopping mall that includes female employees (Muslims and non-Muslims), knowing that each person works in their own section, that one lowers their gaze, and that no other work is available? And what is the definition of prohibited mixing (ikhtilat)?

If a fleeting encounter lasting minutes leads to fitnah (temptation/strife), khalwah (unlawful seclusion), or a woman's soft speech, then it falls under prohibited ikhtilat (unrestricted mixing). If your work section is exclusively for men, you may continue in it, while being keen to lower your gaze and avoid khalwah with women if they come to the section. It is advisable to seek employment free from such prohibitions.