Here's how to fix it in Gnome :)
Settings -> Keyboard -> View and Customize Shortcuts -> Switch windows -> Alt + Tab
And for completeness, on the command line
gsettings set org.gnome.desktop.wm.keybindings switch-windows "['<Alt>Tab']"
gsettings set org.gnome.desktop.wm.keybindings switch-windows-backward "['<Shift><Alt>Tab']"
gsettings set org.gnome.desktop.wm.keybindings switch-applications "[]"
gsettings set org.gnome.desktop.wm.keybindings switch-applications-backward "[]"
This is simultaneously one of the saddest and funniest things I've read about GNOME in a while (which has a surprisingly high bar on both accounts)