MacOS Monterey and MacOS Big Sur introduced a new style to the MacOS alert dialog boxes, which look more like something you’d see in iOS than MacOS. In the new design style for MacOS alert dialog windows, everything is centered with the app icon on the top and the alert messages below, whereas the older traditional style of MacOS alert dialog boxes has always shown an icon on the far left, with the alert information to the right of that.
If you’d like to return to the older traditional style of MacOS alert dialog boxes and windows, you can do so with the help of a defaults write command.