It’s one out of 35. The Space Shuttle disasters killed 14 crew members. Wikipedia says 610 people have reached orbit (or were intended to). Let’s use that as the denominator (so we aren’t counting Jeff Bezos). One in 35 is 2.8%. So, just the shuttle disasters account for 2.2%. Apollo 1’s crew of 3 also died.

But I think they probably just got the 2.8% number from Wikipedia: https://en.m.wikipedia.org/wiki/List_of_spaceflight-related_accidents_and_incidents

As of December 2023, a total of 676 people have flown into space and 19 of them have died. This sets the current statistical fatality rate at 2.8 percent.