Update: A fellow redditor in r/weightroom found a second video of the same squat. According to which it was only 320kg (see 2nd video below). Nonetheless he made it look way too easy.
Here is a video of a big 360kg (800 lbs) 320kg (705 lbs) squat by Behdad Salimi.
Look at the expressions of the other lifters.
Thanks to the anonymous commenter for the link.