The Quran makes a prediction about the military successes of the Byzantines (i.e. the Romans). Here are two translations used by references below of Quran 30:2-4:
The Byzantines have been defeated- In the nearest land. But they, after their defeat, will overcome. Within three to nine years.
The Romans have been defeated in the lowest land, but after their defeat they will be victorious within three to nine years.
The website Miracles of the Qur'an paints this as an impressive miracle:
In short, everyone was expecting Byzantium to be destroyed. But during this time, the first verses of Surat ar-Rum were revealed, announcing that Byzantium would triumph in 3 to 9 years. This predicted victory seemed so impossible that the Arab polytheists thought it would never come true.
The Byzantine victory was completed when Emperor Heraclius defeated the Persian ruler Khosrow II in 630, recaptured Jerusalem, and regained the "True Cross" for the Church of the Holy Sepulchre.179 In the end, "the victory of the Romans" proclaimed by Allah in the Qur'an miraculously came true within the verses' stated "three to nine years" time frame.
A Reddit user, Killawoh argues that the prediction was not impressive at all.
The original Quranic text did not include vowel marks. It didn't exist back then and was added into the text later.
Depending on how you vowelize the words you will get different meanings in Arabic.
Considering the different readings you get depending on the vowels and the fact that vowel points were not added until some time after the Romans defeated the Persians it is possible that the scribe who was tasked with adding vowels to the Quran simply tampered with the text in order to create a "fulfilled" prophesy.
The first site also claims that the location of the victory was predicted - the "lowest place on earth".
Another Reddit user in the same thread, shahryarrakeen disclaims that:
That debunked da'wah poetry video cited a translation that referred to the "lowest point" in 30:2-3 and made a reference to the Dead Sea. Most translations I've seen refer to the "nearest point". Even granting the "lowest point" translation. Antioch, the site of the battle referenced in 30:2-3, is 400 miles north of the Dead Sea. Oops!
Where does the truth lie? Was this an impressive prediction?