Three of the matches are suspended for a period of two years, UEFA said in a press release.
In reality, he is only facing a two-match suspension because Prestianni did not play in the return leg against Real. At that time, he served a provisional one-match suspension.
If Prestianni is included in Argentina's World Cup squad, he will miss the first two group-stage matches. UEFA will ask FIFA to extend the ban beyond Europe.
The 20-year-old was accused of racist abuse by Real Madrid's Vinicius Junior, who claimed Prestianni called him a "monkey".
Prestianni denies the accusation. UEFA instead punished Prestianni on homophobic grounds after interviewing both parties.
