What is the ruling on drinking water after hearing the Fajr adhan in Ramadan? And what is the ruling on a fasting person residing in Jeddah breaking their fast at the adhan of Mecca?

One must abstain from things that invalidate the fast (muftirat) upon the advent of true dawn (fajr as-sadiq). Therefore, if someone drank after the true dawn, and the muezzin was trustworthy, not giving the adhan except after dawn, then their fast is invalid and they must make up that day. However, if they were not certain that their drinking occurred after dawn, or if the muezzin used to give the adhan before the proper time, then their fast is valid.

It is not permissible for a resident of Jeddah to break their fast upon hearing the adhan from Mecca due to the time difference. However, if they broke their fast out of ignorance, their fast is valid. If they intentionally broke their fast, some scholars hold that they must make up that day. So, whoever made a mistake in this regard and did not do so intentionally, their fast is valid and they do not owe a make-up day.