By default, Windows 11 locks the taskbar color to match your system theme (Light or Dark). To unlock custom colors, you have to ensure you are in "Dark" or "Custom" mode.
Windows 11 introduced a sleek, centered taskbar and a refined visual aesthetic built around the "Mica" material design. While the operating system offers fewer direct customization options than its predecessors, changing the taskbar color is still possible — though it requires understanding how Windows 11 links the taskbar to the overall theme and accent color system. change color of taskbar windows 11
If your Windows is not activated, most personalization features will be locked. By default, Windows 11 locks the taskbar color
Scroll down to Accent color and pick a shade you like. change color of taskbar windows 11