Ok I see that there is common misunderstanding about the numbers and colors. Let me try to clarify a bit more.
Those numbers you were typing into the 2023 color picker for the VRay material (for example (5,5,5) as mentioned above)...
Nobody knew those numbers except for you and the old 2023 color picker. Not even the Vray material in 2023 ever saw those numbers. Only you and the old color picker were calling that particular color with those numbers. VRay doesn't know that color with those numbers, Max scene file doesn't save those colors with those numbers, windows or your monitor doesn't show that color using those numbers, Photoshop doesn't call that color you picked with those numbers. Those numbers were created just for the old color picker and lost forever when you click the OK button in the color picker.
Forget about those numbers. It was just the old color picker and you.
When you typed (5,5,5) in 2023 VRay material, the number that the color swatch was seeing was (0.02, 0.02, 0.02), VRay material was thinking that you wanted the (0.02, 0.02, 0.02) color. That's the value saved in the max file, not 5. When that color reached the vray material, (5,5,5) was long gone, as soon as you clicked the OK button of the color picker, that color was known as (0.02, 0.02, 0.02) thereafter.
Proof: In 2023 set one of the Vray mtl colors to (5,5,5). Right click on the color swatch, copy. Paste that color in a color swatch of the physical material. Click that color swatch and see that numbers are 0.02 (yes 2023 had two color pickers, one floating point, one integer and that was bad, unified in 2024).
That (0.02, 0.02, 0.02) never changes. If you open that old 2023 scene in 2024, that color is still the same color and it's still defined as (0.02, 0.02, 0.02), identical to 2023 to the last bit (32-bit float). If you open that that color in 2024 color picker, in the "scene" column you'll see that 0.02 number. That color's name internally is (0.02, 0.02, 0.02) always was and still is.
Thus, there is no need for conversion.
2024 color picker now shows how that color is internally defined in the "scene" column. But also, for your convenience, it shows the standard sRGB integer values which are (43, 43, 43) so that you can copy/paste values between applications etc as Photoshop (and rest of the World) knows that color as (43 43 43) if described in 8bit integers.
Anything describing that color in floating point knows that color as (0.02, 0.02, 0.02).
(vray, max scene, physical material, new color picker's scene column, etc).
Anything describing that color in 8bit integer sRGB knows that color as (43, 43, 43).
(new color picker, photoshop, your monitor, HTML parsers, new color picker's display column, etc).
It was just the old color picker, during its short lifespan, called that color as (5,5,5).
Hope this helps.
Cuneyt Ozdas
Principle Software Engineer