Some Wayland compositors don't provide Alacritty with the information it needs to find the cursor theme, which results n an invisible mouse cursor when over the Alacritty window. You can work around this by telling Alacritty which cursor theme to use, you can do this either by setting the XCURSOR_THEME environment variable, or by symlinking the cursor theme you want to ~/.local/share/icons/default, ie. for Adwaita (the default Gnome theme) run: ln -sf /usr/share/icons/Adwaita ~/.local/share/icons/default