Why is it impermissible for a woman to wear foundation in front of non-mahram men, even though it is not considered "tabarruj" (flaunting/excessive adornment)?

Adorning oneself is not tabarruj (wanton display) unless a woman reveals it to those for whom it is unlawful to look at her. Allah has permitted adornment for women who are not mutabarrijat (those who make a wanton display). Even elderly women are allowed to lay aside their outer garments, provided it is not a tabarruj by revealing their adornment. This is because tabarruj is the act of seeking to appear and uncover, and to display what should be concealed, such as displaying what attracts men's admiration and arouses their desire. Therefore, it is not permissible for a woman to apply dyes, creams, or similar types of adornment if she leaves her home with her face uncovered, due to the Almighty's saying: "And not display their adornment except what appears thereof."