As much as I like to hate on a new OS like the next person, I think it's worth pointing out we're probably not seeing the full picture here:
When trying to reproduce the problem as shown in the article by resizing the Safari window currently displaying the article, the drag cursor changes shape at the visible border of the window, not the shadow and consequently, dragging works as expected.
When trying to reproduce the problem as shown in the article by resizing the Safari window currently displaying the article, the drag cursor changes shape at the visible border of the window, not the shadow and consequently, dragging works as expected.
https://youtu.be/kNovjjvYP8g
This might be an application- or driver specific issue, not necessarily a common Tahoe issue.