Because the Moon's orbit is not in the ecliptic plane (we'd see solar and lunar eclipses every month if that was the case), the Moon varies in declination and therefore also in inclination of its apparent crescent relative to the ecliptic. At times, this can result in unusually steep or shallow angles between the lunar crescent's apparent orientation and your local horizon, at a given phase. The crescent will be "lying on its back" or be more upright to an extent that will vary from one lunation to another.
https://en.wikipedia.org/wiki/Lunar_standstill