At Navan Racecourse on 14 October she was stepped up in class and distance to contest the Listed Staffordstown Stud Stakes over one mile and finished second of the eight runners, beaten one and three quarter lengths by the winner Peach Tree.
She raced in fourth place before making strong progress in the last quarter mile and overtook Who's Steph in the final strides to win by a neck.
[9] In the 241st running of the Oaks Stakes over one and a half miles at Epsom Racecourse on 31 May Tarnawa started a 20/1 outsider and came home eleventh of the fourteen runners behind Anapurna, beaten more than thirteen lengths by the winner.
[10] Tarnawa returned to the track after a break of two and a half months for the Group 3 Give Thanks Stakes at Cork Racecourse and went off the 7/2 second favourite behind Simply Beautiful.
She raced in third before taking the lead in the straight and held off a challenge from the favourite to win by one and a half lengths despite hanging to the right in the closing stages.
[14] For her final run of the season Tarnawa was sent to England to contest the British Champions Fillies & Mares Stakes over one and a half miles at Ascot Racecourse in which she started at odds of 10/1 and came home ninth of the twelve runners behind Star Catcher, beaten just over eight lengths by the winner.
[15] The flat racing season in Britain and Ireland was restructured as a result of the COVID-19 pandemic and Tarnawa did not reappear until 8 August when she attempted to repeat her 2019 success in the Give Thanks Stakes in which she was ridden by Oisin Orr and started third choice in the betting behind the three-year-olds Cayenne Pepper and Passion (respectively second and third in the Irish Oaks).
She gained the advantage 200 metres from the finish and drew away in the closing stages to win "readily" by three lengths and a short head from Raabihah and Dame Malliot.
With Soumillon again in the saddle, she was restrained towards the rear of the field as Tawkeel set the pace from Alpine Star, before making steady progress in the straight.
"[20] For her final run of the year, the filly was sent to the United States to contest the Breeders' Cup Turf at Keeneland on 7 November when she was ridden by Colin Keane and started the 3/1 second favourite behind Magical.
COVID-19 played a part in the arrangements: Soumillon was barred from taking the ride after testing positive for the virus while Dermot Weld was obliged to stay in Ireland, leaving his son Mark to saddle the filly.