i3wm doesn’t provide a compositor like xfce/gnome/kde do (to enable fancy effects), so you’ll have to install a standalone compositing manager. An old i3wm faq mentions compton as compositing manager but there’s also picom (the last fork in a long chain). It seems it’s only a matter of running the manager alongside i3wm (or awesomewm or dwm for that matter).
Sorry, I’m not a i3wm user so I can’t be of more help - I got hit by the same bugs as i3wm users because I had disabled compositing in xfce to decrease bloat a long time ago before an update introduced tearing.
Oh, I stand corrected ; I’ll add those WMs to the troubleshooting doc.