In Windows 11 Insider Preview 26300.8346, the Start button is offset to the left and misaligned

The simplest fix is often to just refresh the process that draws your taskbar.

Press Ctrl + Shift + Esc to open Task Manager, find "Windows Explorer" in the list, right-click it, and select "Restart". Your screen will flicker for a moment, and hopefully, the taskbar will snap back into place

After updating to Windows 11 Insider Preview Build 26300.8346 (released May 1, 2026), the Start button is visually shifted to the left and does not properly align with the center of the taskbar. The button appears offset, creating an asymmetric gap that disrupts the intended centered taskbar layout.

Just roll back to the stable version, or you can wait for Microsoft to fix the issue in a future preview build.