Is it forbidden not to wear the niqab in countries where women do not wear it? And does this invalidate the fast, especially since some scholars have permitted uncovering the face?

Among the negative phenomena is for a woman to commit to covering her face in her own country, but then abandon her niqab when she leaves it. This indicates a weakness in religious deterrent and in mindfulness of Allah. These women should fear Allah and know that He is aware of them, and that the face veil is the adornment of a righteous woman, and a sign of her modesty and chastity. Let not Satan deceive them. For even though some scholars issue rulings permitting the uncovering of the face, they also state that covering it is recommended, and if uncovering it leads to temptation, then covering it becomes obligatory without dispute. This corrupt era necessitates the niqab. A Muslim woman must be diligent in covering her face from the gaze of non-mahram men, whether in her own country or abroad. Uncovering the face does not invalidate the fast, but whoever believes it is obligatory to cover it, or follows those who issue such a fatwa, has committed a sin which may diminish the reward of her fast, due to the Prophet's (peace be upon him) saying: "Whoever does not give up false statements and evil deeds, and ignorance, Allah is not in need of his leaving his food and drink."