At this point it is useful to reiterate that global population growth right now is no longer exponential. Not even linear. It is sublinear, and the population expected to be stabilized around 2070, in the vicinity of 9-10B.
The projections from different research teams differ in when they expect the population population to peak. IIASA suggests what you say, the UN expects it later. I looked at the different projections (and what is behind the differences) here https://ourworldindata.org/peak-child