Lightened color not working with css variable switch in darkmode

[Machy8]

Describe the bug

I have screen:background-color:darken($background,10) which works fine for the light theme but if I do screen&&dark:background-color:lighten($background,10) it does not generate the lighten color from the changed background variable instead is keeping the same value from the light theme.

Reproduction

.

Logs

No response

System Info

.