Whether enabled or disabled, the status bar is always greyed out. Couple updates ago, there was no grey bar and while it looked a little buggy, did show a difference between a grey bar and no grey bar.
I suggest that if it’s totally necessary, to just make little bubbles for the clock and battery/internet connection statuses and have the rest of that space be 100% transparent. Enabling or disabling focus mode does nothing and has been like this for the last few updates. If it’s NOT necessary to have the status bar filled in with a grey bar, then just remove it. I’m not aware if it’s possible or a limitation.