When I openned faceit, everything worked smoothely until the match launches. There, my adblocker was blocking the stuff to join the match.
I saw that ad to use the faceit client, so I downloaded & installed it, and again, everything work fine until I have to join the match : nothing appears. I am forced to use a web browser with desactivated adblocker to join faceit csgo match.
See here a screenshot : https://imgur.com/a/TnVZu
I think it is strange I got the same error in an hour with the client or the web browser. The thing must be somehow glitched.