They've been dealing with DDoS attacks for a few weeks now. If you're on that instance, it would probably do you well to create an alt on a different instance such as lemmy.ml, sh.itjust.works, or lemm.ee that's what I've been doing. Got 2 or 3 accounts I swap to when lemmy.world.is down
We've been targeted too by what's probably a couple of script kiddies trying to brute force their way into our server. Not exactly a DDOS but a similar effect. Just had to remodulate the shields a few times.