P3 color

Check on a P3 display to see the difference.

Japan red

The national flag of Japan is a rectangular white banner with a red circle at its center. The flag is officially called the Nisshōki (日章旗, ‘flag of the sun’) but is more commonly known in Japan as the Hinomaru (日の丸, ‘ball of the sun’).

When you look up the red of the Japanese flag online, the hex value you’ll often find is #BC002D. At first glance, it seems right—but on screen, it reads more like a deep burgundy than the bright, iconic red of the flag. Clearly, this isn’t quite what was intended.

Initially, the color was defined using the Munsell color system as 5R 4/12. Later, in 2008, the Ministry of Defense updated the specifications to: Acrylic fiber: 5.7R 3.7/15.5 Nylon: 6.2R 4/15.2 These values describe a red with a slightly orange hue and high chroma, intended to be vibrant and noticeable in various lighting conditions .

source: https://en.wikipedia.org/wiki/Flag_of_Japan

Also CMYK 0-100-90-0 is mentioned as value. Which roughly converts to #FF001A. Much more of a bright red.

Also check out this page showing the colours of a rainbow both in hex and oklch.