Lightened color not working with css variable switch in darkmode

### 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

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### Logs

_No response_

### System Info

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