[5] Prior to kick-off a minute's silence was observed in memory of the victims with both Nice and Rennes wearing unique commemorative shirts bearing the names of those who had died.

[11] Competing with Maxime Le Marchand and new loan signing Marlon, Sarr saw his game time slightly reduced but still managed to record 29 appearances across all competitions for the campaign.

[15] On 21 October 2020, Sarr made his Porto debut during their UEFA Champions League group stage tie with Manchester City, featuring for 80 minutes before being replaced by Evanilson in the 3–1 away defeat.

Following proposed loan moves to Germany, Italy and France reportedly collapsing,[19] Sarr opted to stay at Chelsea and was subsequently given the number 31 jersey for the forthcoming 2021–22 campaign.

On 22 September 2021, Sarr made his Chelsea debut during a 1–1 draw in the EFL Cup against Aston Villa, featuring for the full 90 minutes as the Blues progressed to the fourth round following a 4–3 penalty shootout victory.

[20] A month later, he made his Premier League debut against newly-promoted Brentford due to the unavailability of Antonio Rüdiger and Thiago Silva, playing the full 90 minutes and keeping a clean sheet during the 1–0 victory.

[26] In February 2024, Le Havre sporting director Mathieu Bodmer criticized Chelsea for the collapse of a proposed loan deal that would have covered the remaining 18 months of his contract.