How can abstaining from food and drink five minutes before Fajr be an innovation (bid'ah), despite Anas's narration from Zayd ibn Thabit that "a period sufficient for reciting fifty verses" separated the Suhoor from the Adhan of Fajr?

Delaying the suhoor (pre-dawn meal) is recommended until the Fajr (dawn) adhan (call to prayer), based on Allah Almighty's saying: (And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]). The Sunnah is to cease eating at the onset of Fajr, not before that as a precaution. The hadith about the Prophet, peace and blessings be upon him, having his suhoor before the adhan by a time equivalent to reciting fifty verses indicates delaying the suhoor, not abstaining from food before Fajr.