/usr/share/sddm/themes/ubuntu-theme/ is a symlink set up by 'alternatives' system by sddm package install scripts
On all flavours that use sddm it links as: ubuntu-theme -> /etc/alternatives/sddm-ubuntu-theme/
Each flavour with its sddm theme config then makes /etc/alternatives/sddm-ubuntu-theme/ point to their sddm theme folder.
So on studio that points to /usr/share/sddm/themes/ubuntustudo/
That means that the file /usr/share/sddm/themes/ubuntu-theme/Main.qml in question is actually physically on disk the real file /usr/share/sddm/themes/ubuntustudo/Main.qml which is shipped in ubuntustudio-default-settings package.
/usr/share/ sddm/themes/ ubuntu- theme/ is a symlink set up by 'alternatives' system by sddm package install scripts
On all flavours that use sddm it links as: ubuntu-theme -> /etc/alternativ es/sddm- ubuntu- theme/
Each flavour with its sddm theme config then makes /etc/alternativ es/sddm- ubuntu- theme/ point to their sddm theme folder.
So on studio that points to /usr/share/ sddm/themes/ ubuntustudo/
That means that the file /usr/share/ sddm/themes/ ubuntu- theme/Main. qml in question is actually physically on disk the real file /usr/share/ sddm/themes/ ubuntustudo/ Main.qml which is shipped in ubuntustudio- default- settings package.
Hope that clears things up.