At least for me the problems start when 15+ people join the call (about the size of a small classroom). I've tried both their hosted platform and self-hosting ¯\_(ツ)_/¯
Setting is up is easy but the user experience is really bad :-( I'm on Google fiber and Google Meet works great and even MS Teams works fine. But whenever I use Jitsi either A) the call participants keep getting disabled/enabled or B) when video does come through my computer crumbles to its knees. Oh, and by the way, good luck using anything other than Google Chrome!