If someone discovered something that invalidated their fast after the end of Ramadan, must they repeat fasting the previous Ramadan?

Scholars have differed concerning one who commits an act that invalidates the fast out of ignorance: must he make up the fast (qaḍāʾ) or not? The more cautious approach is to make up the fast to avoid disagreement. However, the preponderant opinion is that he does not have to make it up, based on the Almighty’s saying: ﴿that I may warn you thereby and whoever it reaches﴾. Thus, the obligation is not established until after the message has reached.