The encounter at Stadio Friuli saw Maignan report alleged racist chants to referee Fabio Maresca, claiming that he had been subjected to despicable m chants from Udinese fans behind his goal.
Despite a stadium warning and the threat of the match being postponed, the chants persisted, and Maignan walked off down the tunnel with his teammates in tow as Udinese players pleaded with supporters to desist.
The game eventually resumed following a brief pause, with Maignan taking his place in between the sticks, and Stefano Pioli's side travelled back to San Siro with a 3-2 win in the bag.
However, the result paled into insignificance due to the abuse suffered by Maignan, who had already been the victim of racist chanting by a Juventus supporter shortly after arriving in Serie A from Lille in 2021.
The France international opened up on the latest incident after Milan's slender victory, claiming that "very strong sanctions" must be handed down to guilty parties, and Udinese have now announced that the individual "primarily responsible" for the abuse has been banned for life.
"Udinese Calcio communicates, following the identification of the person primarily responsible for the deplorable racist insults against Maignan, that the person in question will be banned from our stadium for an indefinite period with immediate effect," Udinese said in a statement.
"The club confirms its commitment against racism and considers it essential to apply strong measures to send a concrete message against discrimination, not only in football, but in society.
"The Club promptly, starting from Saturday evening, worked in close collaboration with the Authorities, making available all its cameras and the cutting-edge equipment with which the Bluenergy Stadium is equipped in order to provide rapid feedback on the investigations still underway.
"Udinese thanks the Udine Police Headquarters for their collaboration and confirms its firmness in targeting those responsible for the insults that tarnish the sporting ethics of the club, the Region, the city of Udine and of a fan base that has always been a model of integration and respect."
The sickening abuse suffered by Maignan came on the same weekend that Coventry City's Kasey Palmer was targeted by a m gesture from a Sheffield Wednesday supporter in their Championship encounter, which was condemned by both clubs.
FIFA president Gianni Infantino has now led calls for teams to automatically forfeit a match if their fans are found to have racially abused players, while Omar Beckles - chair of the Professional Footballers' Association - has urged authorities to identify and bring criminal charges against the supporter to have allegedly targeted Palmer.