GVFs metadata is not supported [duplicate]

I changed the gnome shell theme of the login screen to Yaru-dark by following instructions in this answer. I did notice the dark calendar and system menu when I log on after reboot. However, when I lock my computer with Super+L, the lock screen still has white calendar and system menu, so I would like to make those dark as well.

All the answers I've seen so far are for Ubuntu 18.04, since they refer to /usr/share/gnome-shell/ubuntu.css which I do not have. I do have a /usr/share/gnome-shell/gnome-shell-theme.gresource, but changing that to my dark theme gresource still results in light shell on lock screen. Some other answers refer to a /usr/share/gnome-shell/theme/gdm3.css, which I do not have either (the only css file I see in that directory is a gnome-classic.css).

I would just like to know which css file or which gresource file controls the lock screen theme on Ubuntu 20.04.

In a fresh install of Ubuntu 20.04, the default shell theme.. and lock screen both are configured to use the css file

Yaru/gnome-shell.css which is inside the /usr/share/gnome-shell/theme/Yaru/gnome-shell-theme.gresource

this is configured in the file /usr/share/gnome-shell/modes/ubuntu.json

{
    "parentMode": "user",
    "stylesheetName": "Yaru/gnome-shell.css",
    "themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",
    "debugFlags": ["backtrace-crashes-all"],
    "enabledExtensions": ["[email protected]", "[email protected]", "desktop-icons@csoriano"]
}

So, you can pointout what ever .gresource file you want to use and the corresponding gnome-shell.css

for example, If I want Yaru-dark theme, I can simply point out like this by editing the file /usr/share/gnome-shell/modes/ubuntu.json

Take Backup of the file /usr/share/gnome-shell/modes/ubuntu.json before editing

{
    "parentMode": "user",
    "stylesheetName": "Yaru-dark/gnome-shell.css",
    "themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",
    "debugFlags": ["backtrace-crashes-all"],
    "enabledExtensions": ["[email protected]", "[email protected]", "desktop-icons@csoriano"]
}

Please note that Default shell theme and lock screen uses same file.. so If you want Yaru shell theme for the desktop session.. you need to install it as a local theme which is another topic.

I have not tried with full path of the .gresource file.. in the line

"themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",

this means.. theme/Yaru/gnome-shell-theme.gresource is a relative path of the base /usr/share/gnome-shell