How to get Windows 10 light blue color on Windows 11?

By default, Windows 11 disables colored title bars and taskbars when you are in Light Mode . If you want to see your light blue accent color on the taskbar while keeping the rest of the system Light.

You can also use a third-party tool like the "Windows 11 Theme Editor" or "Accent Color Changer" to customize the accent color.

Settings > Personalisation > Colours > change "Choose your accent colour" to Manual > click "View colours" at the bottom > hit the "+" tile > when that picker opens, clear the hex box and type 0078D7, then press "Done"

That's the exact Windows 10 blue, Microsoft just stopped including it as a default.