First, good that you think about accessibility!
I don't have an immediate answer, more a theory. This could be a bug.
Sometimes websites have texts outside of the viewport with information for visually impaired users, the information could be info on how to navigate with a keyboard. It is possible to make the screen reader ignore the element.
Maybe this is a use case in Construct. Just guessing.
In web the button would be picked upl, in Constract that seems unnecessary to me.
Depending how the elements are set to invisible in web has an impact on how the screen readers approach those elements.
Screen readers behave differently, usually good to do QA with multiple readers.