My understanding was that unless you were rooted Twilight doesn't actually filter out blue light. Instead it does a red overlay. That makes the screen brighter

My understanding was that unless you were rooted Twilight doesn't actually filter out blue light. Instead it does a red overlay. That makes the screen brighter which lets you turn down the overall brightness resulting in less blue light but it's not as good as a true blue light filter that actually removes blue (which is what the built in support does and why it needed hardware support). Edit: And adding a little more I just read, because it uses a red overlay it red tints what was pure black pixels which isn't helpful.