ARIA spec for spinbutton::

Authors SHOULD set the aria-valuenow attribute when the spinbutton has a value.
Default for aria-valuenow is that there is no current value

I think this is problematic because if role=spinbutton is on the HTML <input>, then this can have a value and the HTML attribute always takes precedence over the ARIA attribute. I.e. an ARIA attribute is then unnecessary and if aria-valuenow and value have different values, it is theoretically so that value wins and aria-valuenow is ignored, but practically it is so that here every browser does something different and the screen readers in turn ignore the information of the browsers to the Accessibility API, so that a big chaos arises.

In addition, it could be considered whether a value could also result from the text content for spinbuttons that are not located at an <input>, and thus aria-valuenow would then also be superfluous. Like with role=textbox:
<div role=spinbutton tabindex=0>3</div> .
This is also interpreted differently by browsers (in Firefox this spinbutton has no value, in Chrome the value is 3).