Consider the below image from the documentation and desired look image.
The hint background color is transparent and is fine for other container types.
However, if you have a gray page, then the above image will look like the hint is cutting out a piece of the SfTextInputLayout, which makes it look "broken".
Ideally, when Container type is set to Outline, we would prefer to have the hint background color to be the same as the ContainerBackgroundColor. That way it will make the hint box look like its part of the SfTextInputLayout.
Alternatively, we must set page color to be same as
If this would go forward, then maybe it would be a good idea to round that tiny hint box corners too thorough a property. And the option to add borderline just to make it look more seamless.