The universe itself may be unnatural

But inflation is particularly interesting when it comes to the question of spatial curvature. There were originally three fine-tuning problems that served as motivation for it:

The fact that the Universe was the same exact temperature in all directions to 99.99%+ accuracy, despite those distant regions not having time to exchange information. (The horizon problem.)

The fact that the Universe was observed to have zero spatial curvature (less than 0.25% today), despite the wide variety of possibilities that would lead to a habitable Universe today. (The flatness problem.)

And the fact that there were no high-energy, relic particles that an arbitrarily hot-and-dense Universe would inevitably lead to. (The monopole, or relic, problem.)