I just noticed that in 2.90 that the values of the Debug sample count are clamped or normalized to 0-1.0. This is fairly uncommon for debug and stats aovs. And the render times aov seems not to be normalized, so it is also inconsistent.
I would love to see this changed as it makes life easier to debug inefficiencies.
Bug report for reference: https://developer.blender.org/T78590