It was Saina's fourth straight loss to world No. 12 Busanan.
The world badminton champion took to Instagram to express her greetings.
Parupalli Kashyap exited from the tournament after he retired in the third game of his first-round clash against Canada's Jason Anthony Ho-Shue owing to a calf injury.
It was a chaotic day and the entire procedure put us under severe mental stress, the duo told Malayala Manorama.
Both the Badminton World Federation (BWF) and Badminton Association of India (BAI) confirmed the development.
Months after the COVID-19 pandemic disrupted the international calendar, Sindhu, seeded sixth, returned to action with a 21-16 24-26 13-21 defeat to world no 18 Blichfeldt in a 74-minute battle.
A December poll by public broadcaster NHK showed a third of Japanese residents want the Games to be scrapped due to fears an influx of foreign arrivals may cause a further spike in COVID-19 cases.
Saina's grievances was chiefly about players allegedly not being allowed to interact with their physios and trainers and the reduced practice and gym timings allowed.
The 25-year-old world badminton champion, who is part of the Target Olympic Podium Scheme core group, spoke to Malayala Manorama over the phone from London before heading for Thailand.
They will compete in back-to-back BWF World Tour Super 1000 events in Thailand.