The 26-year-old joined the Brazilian giants on loan last summer and he has since played 48 times across all competitions, including 24 appearances in the 2022 campaign.
According to Brazilian journalist Vene Casagrande, Flamengo have the option to sign Pereira permanently for €10.5m, but they have instead informed Man United that they would prefer to keep him on loan until December.
However, the Red Devils have rejected this proposal and Flamengo are unwilling to activate their option-to-buy clause, meaning the midfielder will return to Old Trafford this summer.
Casagrande adds that United are open to selling Pereira and they have received a cash offer from an unnamed club which is higher than the €10.5m they initially agreed with Flamengo back in February.
Pereira, who has just a year remaining on his contract at Old Trafford, has made 75 senior appearances for Man United since making his debut in 2014, and he has also had spells out on loan with Granada, Valencia and Lazio.