Shutter speed itself does not directly change the moon’s color; it mainly changes exposure. The color shift is most likely coming from processing in the camera or software, not from the moon.

Based on the answers, the most likely cause is auto white balance. In one exposure, the moon may have been bright enough for the camera to treat it as the key neutral subject. In the darker exposure, the camera may have taken more of the surrounding sky into account, shifting white balance and making the moon look warmer/oranger.

Tonal curves and saturation can also change slightly with brightness. A brighter moon may be rendered less saturated or closer to white, while a darker one can appear to have more color.

If you want consistent moon color, use a fixed white balance instead of AWB, and compare the images from the same RAW processing settings. That will help separate true exposure changes from automatic color adjustments.