That is a shutter glass. You can tell by the two leads, positive and negative. Just like an old calculator, it is at it's dimmest when there is no current, disconnected, because when you add current the liquid crystals align to let light through. I don't know if that is a pure on/off shutter, or if it can set to a variable brightness. I also don't know how responsive it is, how many cycles on/off per second. There could be a portion of the firmware controlling this, or it could be all on a chip preassembled somewhere else. But it probably is set either timing-wise or a combination of timing and variable shade (which makes more sense) to dim at just the right time and just the right shading to hide/shudder the motion blur. It's a clever way to do it. But I wonder if Pimax would let us know if that can be something we can be given control of, or if someone can eventually allow us a handle to hack it in the firmware. It's not a priority for me, but I would like to try it either off or taken out too. Pimax is a very tolerable but bit too dim, but I don't have it set up just right yet.
As for the blue light, that has nothing to do with the shutter/filter. Many phones and other Devices, lcd and oled, are getting blue light "filtering" software to help with eye fatigue as well as mitigate the effects that the blue hues of normal range LCDs have on mental fatigue and inhibiting sleep by eliciting chemical responses in the brain, such as inhibited melatonin production. This is a new trend and on the phones and tablets I have I usually turn them off for myself, but leave them on for my kid. Except that I use a program on my desktop to give me better blue-less shades at night that can help one get to sleep earlier. https://justgetflux.com/
The sun is actually not yellow, it's white. But the atmosphere makes it appear yellow, and our biology has adjusted to that shade of light to know when to sleep and other things. The blue-light thing is just turning down the blue on all of these phones. As for whether being a few inches from a too bright screen will burn out your eyes and cause early macular degeneration, you'll have to think more and research that further if that's a concern for you. I've been hunched over screens for the last 30+ years and I can still see fine. But yeah, this in your face thing is something to think about.