What if i forgot and ate while fasting non- Ramadan days (making up missed fasting days)?

The renowned scholars Imam Abu Hanifa, al- Shafi’i and Ahmad agreed that if a fasting person ate or drank out of forgetfulness during the daylight, his/her fast remains valid and no making up is necessary.

Textual evidence
Allah the Almighty says in the Quran, “Our Lord! Punish us not if we forget or fall into error”(2:286)
It was also narrated by Abu Hurayrah that the Prophet (peace and blessings be upon him) said: “Whoever forgets when he is fasting and eats or drinks, let him complete his fast, for it is Allah who has fed him and given him to drink.”
This ruling stands whether the person is fasting an obligatory or supererogatory fasting as there is no differentiation on that matter.