I may have found the exact answer this question: "Injuries - Who, when, how long?"
(credit:
https://sempremilan.com/a-full-breakdown...his-season)
September 2020
➤ Romagnoli: calf muscle injury since August. Returned Inter-Milan on 17 October
➤ Ibrahimovic: positive for Covid. Returned Inter-Milan on 17 October
➤ Rebic: elbow injury in Crotone-Milan. Returned Udinese-Milan on 1 November
October 2020
➤ Gabbia: positive at Covid with the Italy U21 team. Returned Milan-Verona on 7 November
➤ Donnarumma: positive for Covid before Milan-Rome. Returned Udinese-Milan on November 1st
➤ Hauge: positive for Covid before Milan-Roma. Returned Udinese-Milan on November 1st
➤ Castillejo: muscle fatigue in Milan v Roma. Returned Napoli-Milan on 22 November
November 2020
➤ Ibrahimovic: muscle injury in Napoli-Milan. Returned Milan-Turin on 9 January
➤ Bennacer: muscle fatigue after Napoli-Milan. Returned Milan-Parma on 13 December
➤ Leao: muscle injury with the Portuguese U21 national team. Returned Milan-Parma on 13 December
➤ Castillejo: knee inflammation after Napoli-Milan. Returned Sampdoria-Milan on 6 December
December 2020
➤ Ibrahimovic: discomfort in the calf. Returned Milan-Turin on 9 January
➤ Kjaer: muscle injury in Milan-Celtic. Returned Benevento-Milan on January 3rd
➤ Bennacer: muscle injury in Milan-Parma. Returned Bologna-Milan on 30 January
➤ Gabbia: knee injury in Milan-Parma. Returned Milan-Crotone on 7 February
➤ Rebic: foot injury. Skipped Sassuolo-Milan, returned Milan-Lazio on 23 December
➤ Saelemaekers: muscle injury in Lazio-Milan. Returned Cagliari-Milan on 18 January
January 2021
➤ Rebic: positive for Covid before Milan-Juve. Returned Milan-Atalanta on 23 January
➤ Krunic: positive for Covid before Milan-Juve. Returned Milan-Atalanta on 23 January
➤ Theo Hernandez: false positive for Covid. Skipped Cagliari-Milan, returned vs. Atalanta.
➤ Calhanoglu: positive for Covid. Returnsed Milan-Crotone on 7 February
➤ Bennacer: bronchitis after Bologna-Milan. Returned Spezia-Milan on 13 February
➤ Mandzukic: contusion in Milan-Atalanta. Skipped the Coppa Derby. Returned for Bologna-Milan
➤ Kjaer: muscle injury in the Coppa Derby. Returned for Spezia-Milan on 13 February
➤ Brahim Diaz: muscle problem in Milan-Atalanta. Returned for Milan-Inter in the league
February 2021
➤ Rebic: injury before Spezia-Milan. Returned for Milan-Inter
➤ Tonali: fever after Bologna-Milan. Skipped Crotone, returned against Spezia
➤ Mandzukic: muscular problem in Red Star-Milan. Return to be defined
➤ Bennacer: muscular problem in Red Star-Milan. Return to be defined
➤ Calhanoglu: muscle edema in Roma-Milan. Return to be defined
➤ Ibrahimovic: muscle injury in Roma-Milan. Return to be defined
➤ Rebic: muscle injury in Roma-Milan. Return expected vs. Udinese