China suffered for about 300 years. Byzentium was down for the count for at least 80 years.
Other areas, e.g. the realm of the Arabs who looked to Mecca for economic direction, didn't notice anything had gone wrong (relative to their earlier condition). They ended up conquering pretty much the rest of remaining civilization.
There were losses beyond imagining ~ for example, Michaelangelo was the first artist in a millenum who could produce sculpture the equal of the best produced by sculptors in Classical Times.
That's how much knowledge of that particular technology (sculpting) that had been lost.
Mohammed was born some 35 years after this event. I am not sure how much of an impact it would have had on Islamic conquests 100+ years later. But you are correct that the impact would have certainly made it easier for Islam to get a foot hold in a much weakened Byzentium empire.
Much of the technology of the time before the Dark Ages was safeguarded by monks all over Europe.