You do realize he's become injury prone, right? This is his injury record since the start of 2017/18 season...
https://www.transfermarkt.com/ousmane-dembele/verletzungen/spieler/288230
Sept 17, 2017 - Jan 1, 2018 -- Hamstring injury
Jan 15, 2018 - Feb 10, 2018 -- Torn muscle bundle
Jan 21, 2019 - Feb 8, 2019 -- Ankle injury
Mar 14, 2019 - Apr 9, 2019 -- Torn muscle bundle
May 5, 2019 - June 16, 2019 -- Hamstring injury
Aug 19, 2019 - Sept 22, 2019 -- Hamstring injury
Sept 27, 2019 - Sept 30, 2019 -- Muscle injury
Nov 28, 2019 - Feb 13, 2020 -- Hamstring injury