Is it obligatory to make up the entirety of the Ramadan fast for someone who used to have suhoor and drink during the Fajr adhan, believing that was permissible, based on what she was told about the practices of some people in Saudi Arabia?

If the muezzin gives the adhan (definition) precisely at the break of dawn, then one must abstain from food and drink as soon as the adhan is heard, in accordance with the Almighty's saying: "And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]. Then complete the fast until the night." (Al-Baqarah: 187). So, if a fasting person eats after the adhan of the true dawn, then their fast is broken, and they must make up for it. However, if the muezzin gives the adhan before the time for dawn enters, there is no harm in eating while the adhan is being called, as the determining factor is the break of dawn. But, if a woman was unaware of the religious ruling, her fast is valid, and she does not have to make up for it, because things that break the fast only invalidate it under three conditions. Her situation is like that of Adiyy ibn Hatim, may Allah be pleased with him, when he ate after dawn, thinking it was permissible, and the Prophet, peace and blessings be upon him, did not order him to make up for it.