Almost every social media site (FB, Reddit, YT, Twitter) and online newspaper comment section has a good share of spam and harassment anyway, it’s up to “an algorithm”, moderator, or verification system to remove as much as feasible.

I’m more thinking of servers unexpectedly down or purged, people hijacking or spoofing others’ profiles, etc. which the way the Fediverse network is setup should make it a little more resilient overall.