Ruslan, if you look at older — dare I say, "historical?" ;) — screenshots, you can see that button placement differs considerably between OS platforms.
The Guidebook GUI Gallery website is an awesome resource to compare such details.
I haven't seen any research yet on the impact of left/center/right alignment of buttons in dialogs, but the general rule of striving for consistency applies to button placement as well, of course.
Placing key widgets in the same relative location in every context makes it easier for users to find them, and it reduces error rate. In particular, this applies to the key Cancel/Confirmation button pair.
Both macOS and Windows have defined simple principles on where to place those buttons, and which order they need to be in: you'll typically find those buttons in the botton right corner of a dialog on both OSs. This convention dates back to Mac OS 7 from 1991 and to Window 95/NT4 from 1995/1996. (As seen, e.g., in Open File dialogs or Time and Date Settings.)
So I wonder: have you observed changing button placements for dialogs (or, rather, alerts) that contain more than one button, Ruslan? If not, maybe it was a purely aesthetic consideration for that particular one-button case?