"Apply gradient across stroke" shows terrible banding compared to a standard linear gradient
When applying a gradient to a stroke with the "apply gradient across stroke" option selected, the resulting gradient is very poor quality, with lots of visible banding.
In the attached image the top gradient is formed by feathering a rectangle with corner radius of 31.235 px by 20px. The quality is fine, although feathering makes specifying specific colours a hassle.
The middle object is the same rectangle with a 40pt stroke, with a white-to-black gradient applied with "apply gradient across stroke" selected. The gradient is very uneven, showing clear banding.
The bottom is a the same linear gradient applied as a fill over a 40px-tall rectangle. Its gradient is smooth without visible banding.
The document is in RGB colour mode and all the colours in the document are specified as RGB black (#000000) or white (#FFFFFF). The screenshot is taken at 100% with pixel preview disabled. Enabling pixel preview makes the gradient quality even worse (see the second attachment).
I would expect stroke gradients to look equally high quality as conventional gradients or as gradients formed by stacking a feathered shape over a background.
Egor Chistyakov commented
That's because stroke's gradient is mesh-based.