What defines the background of this pop-up in the theme?

My theme (a variation of Noctis) has some transparency in it. However in some cases this is not desirable. Like in the case below.

What in the theme definitions define the transparency of this (type of) pop up? Rather have (only) pop ups not have any transparancy.

Should be primary-background-color .

To soften the transparent effect, you can try


mdc-dialog-scrim-color: rgba(0, 0, 0, .5)
mdc-dialog-backdrop-blur: .5vw 

If people ever look for a solution, it should be:

 mdc-theme-surface: rgba(43,55,78,1)