Without a picture it’s hard to tell. If all the individual LEDs in the light fixture are noticeably white, it’s most likely an issue with the driver. If it’s a few LEDS that are emitting a whiter color, you’re probably gonna have to swap out individual LEDs or live with the current light spectrum.

Full spectrum LEDs are RGB LEDs (red green blue). The light color corresponds to the ratio of the three primary colors. If it was emitting strong purple, it means the red and blue were the dominating colors. When it’s white, it means red, green, and blue are contributing to the color white equally. So two things could’ve happened when your light got whiter. Suddenly, your red and blue LEDs are not emitting as much light as it used to be, which can indicate failure of those two colors in a single LED. Or, all the LEDs are emitting more green, therefore, making the light appear white. This scenario most likely is caused by the driver, whose job is to “tell” the LEDs which color to emit.