At the age of 18, she placed sixth in the 200 metres at the 2020 Tokyo Olympics, having made the final along with fellow Namibian sprinter and eventual silver medallist Christine Mboma.

On 3 October, Masilingi competed at the Kip Keino Classic meet in Nairobi, Kenya and improved greatly to set an African U18 best and Namibian senior record of 50.99 s.[13][14] Afterwards, she was offered a full scholarship from the University of Oklahoma.

[19] She was withdrawn from the 400 metres race at the postponed 2020 Tokyo Olympics; the Namibian athletics federation announced that she would compete in the 200 m event for which she also qualified.

[4] In July 2021, the Namibian National Olympic Committee announced that Masilingi and fellow Namibian sprinter Christine Mboma would not be allowed to compete in the 400 m event at the Tokyo Olympics,[6][20] due to World Athletics rules introduced in 2018 requiring that athletes with certain XY DSDs participating in women's running events from 400 metres to one mile cannot have blood testosterone levels above 5 nmol/L.

[8][21] Masilingi and Mboma underwent a medical assessment at a training camp in Italy in early 2021, at which they tested positive for elevated testosterone levels due to a naturally occurring genetic condition.