Lockscreen color

Hi,

I use a password picture to login to Windows. On the left side where it shows the username and 'Sign-in options' it has a band of colour (see attached). On my Windows 10 installation, the colour seemed to be the same as what is set in my personalisation settings. When I upgraded to Win 11 the other day, it is now showing as black and the personalisation colours don't affect it.

Does anyone know how to change this?