1. The blue light is physically behind the others wavelength;
2. The blue is (much) more intense than other wavelengths.
Some background.
The LCD panel is a RGB filter in front of a white light.
White light is usually* made with a blue diode with some phosphor on top. The phosphor converts some (but not much) of the blue light into the rest of visible spectrum. Most of emitted light is the original blue from the diode.
Fun fact: The sun is also mostly blue. And there are white lights that are pretty much only blue, but we perceive as white (usually sold for vegetative growth of plants).
* In the past we used fluorescent tube. Quantum dot film are becoming common now (they have been used for a while, but are mainstream now because Rec. 2020). There are white diodes, but I haven't heard about them being used as backlight -- their CRI are pretty terrible, and they are expensive.