This appears to be a bug with the color picker built into the base color.
Using built in picker:
Plugging in a color picker:
The same values were used for both. The built in picker appears to not be applying the correct sRGB remapping. Here is a picker where I have manually transposed the linear hex value into the sRGB hex slot. Notice it is the same shade as the first image.
You should submit a bug report.
In the meantime, the work around is to use the vector 3 node and manually plug it into the base color.