I am using the 2D Animation preset and so far every new scene I made had the same bright white background. Now my two latest scenes (created with 'copy settings') have a light grey background even though they are set to white. There's also no difference in surface, nodes or strength.
"White" is not an absolute value. The values change depending on the transforms used in the color management section.
If you are using sRGB, with a sRGB view transform, white should be 1.
But If you are using filmic view transform, white is at a value of 16.29
The Color Management settings can be found in the Render Properties :