You're looking at a scaled version of the bitmap (potentially re-scaled multiple times) and some or all of those interpolations may not have been done in a line

You're looking at a scaled version of the bitmap (potentially re-scaled multiple times) and some or all of those interpolations may not have been done in a linear colour space. But in this case I think it's just wrong. The entire first 40% of the bar is black, and I don't think it should be.