The Watchtower—Public Edition, No. 2, 2021, page 7:
In three years, the COVID-19 pandemic resulted in some 6.9 million deaths worldwide.Not certain what the print version actually said, but this doesn't math.
(It would reasonably have been some time in 2023. The download page for the PDF says it was last modified on 20 December 2023. However, many of their online PDFs have that same last-modified date without changing any of the actual content, suggesting some unrelated technical change at that time. So it can't be determined exactly how or when the statement about the pandemic was modified unless someone has the original or intermediate versions.)