Singapore Airlines released this statement:
Singapore Airlines flight SQ321 with 9V-SWM, operating from London (Heathrow) to Singapore on May 20, 2024, encountered severe turbulence en-route.
The aircraft diverted to Bangkok and landed at 1545 hrs local time on May 21, 2024.
We can confirm that there are injuries and one fatality on board the Boeing 777-300ER.
Singapore Airlines offers its deepest condolences to the family of the deceased.
Update 1:
Data from Flightradar 24: