Given the timescales that humans operate on, it would be incredibly strange for us to reproduce into extinction. As far as direct effects, an unmitigated exponential growth trend would eventually result in widespread famine and other resource restrictions leading to a population-limiting amount of death. Not extinction, but not much fun either.

Long term accumulating issues that become unrecoverable past a tipping point could be a source of extinction (e.g. extreme worst case climate change). Here, yes, exponential growth could hasten extinction in a world where people weren't trying to stop the catastrophe, but...

1. Empirically, we're not on an exponential curve or anything close to it. Many developed countries would be in population decline without immigration.

2. Generally, the best solution to problems of efficiency or long term threats is improved technology, not reducing population. In the concrete case of climate change, cutting emissions per capita by >50% is both achievable and clearly superior to the Thanos approach.

3. More people can produce a more interesting universe to live in. Imagine a solar system colonized with 10 trillion humans: provided we build the requisite efficient infrastructure to unfetter human creativity, we would have the capacity to produce over a thousand times as many isekai animes.