CF.lumen Review

Unlike a red overlay, this app converts all screen colors to grayscale first, then shades them red, so completely green text becomes a shade of red rather than becoming unreadable black.

Unlike an overlay, the dark mode affects the notification bar and even the shutdown screen

The master color filter setting also has an option for colorblindness enhancement, with settings for protanopia/anomaly, deuteranopia/anomaly and tritanopia/anomaly. These options in theory enhance clarity and color detail.