All growth has to stop at some point, not just population. But if we want population to grow as much as possible, we can add a few more digits before we hit the planetary limits of anything other than stupidity and political short-term-ism.

(On the other hand, stupidity and political short-term-ism are exactly why we now have problems with loss of biodiversity, antibiotic resistance, a disrupted nitrogen cycle, phosphorus waste, a quarter of the CO2 in our air being artificial, boom-and-bust economic cycles, etc.)