It does seem worth noting that 4→8 billion took 48 years (1974–2022), whereas 2→4 billion took 47 years (1927–1974). So at the very least the growth rate is not

It does seem worth noting that 4→8 billion took 48 years (1974–2022), whereas 2→4 billion took 47 years (1927–1974). So at the very least the growth rate is not entirely novel in the range that you quote. By contrast, 1→2 billion took 123 years (1804–1927), according to the estimates of at [1], though Wikipedia suggests that data prior to the 20th century may be unreliable. [1]: https://en.wikipedia.org/wiki/World_population_milestones https://en.wikipedia.org/wiki/World_population_milestones