Alt+Tab is used to tab through windows. Alt+Shift+Tab is used for doing the same but backwards because this is what I noticed to be somewhat standardized on all relevant systems and environments I know.
Other than that I established a concept on how to work with the keyboard: Alt+… is used for everything WM related, Alt+Ctrl+…controls windows and Alt+Shift+… lefts out windows (it shifts the focus to the desktop).
For example:
Alt+Shift+Left/Right switches to the left or right virtual desktop in labwc on my computer.
Alt+Ctrl+Left/Right moves the currently active window to the left/right desktop.
On Hyprland on my laptop I use Alt+Shift+Arrows to move the focus in that direction.
With Alt+Ctrl+Arrows I move the window in that direction. * Alt+Ctrl+Shift+Arrows resizes the window in that direction
On both I use Alt+Drag&Drop to move windows
Alt+Mousewheel switches to to the next/previous virtual desktop
Alt+Ctrl+Mousewheel moves the window to the next/previous desktop