As you may have noticed, taskbar icons are centered by default since Windows 11.
If you want to put these icons and the Windows 11 start menu back on the left, open the start menu and click on : Settings.

Then, go to : Personalization -> Taskbar.

Scroll down and click on : Taskbar behaviors.

Then, for the "Taskbar alignment" option, select "Left" instead of "Center".

Now, the icons are left-aligned, so the start button is back in its original place.