How can I tell if I am running Wayland?

Open the terminal and type in:

echo $XDG_SESSION_TYPE

You could install mesa-utils-extra and run es2gears_wayland If the app runs, you are running Wayland.

For a fun way to check whether a specific app is using Wayland or XWayland, run xeyes. The eyes will move if the cursor is over an X or XWayland window.

Or run this in a terminal:

env | grep -i wayland

If there is no output, you are not running Wayland.

Use that command in the Ubuntu terminal:

echo $DESKTOP_SESSION

Look at the value returned. If on wayland it will return

gnome-wayland

ubuntu-wayland  #  Ubuntu 20.10