YDI.
Would have been better to post in an out of the loop community, because it definitely reads like shit-stirring. Especially "neo-nazi" admins of dbzer0. Like holy shit that's so far off the mark I have trouble taking it in good faith.
Anyway, I don't have context about the world admin being a zionist or not. But this comment lays out the rest of the events pretty clearly.
In short: an anarchist.nexus (piefed sister site to dbzer0 being on lemmy) admin set their display name to something intentionally shit stirring like "death to all zionists". A lemmy.world admin took it personally for some reason, and instead of reaching out to other admins on anarchist.nexus or dbzer0, reporting it, publicly announcing what was going on, or even running it by the other lemmy.world admins first, they just decided on their own to defederate from anarchist.nexus entirely.
As soon as dbzer0/anarchist.nexus admins learned what was going on, the admin with the shit stirring display name stepped down. Lemmy.world has refederated with anarchist.nexus, but the admin that took it personally is still holding onto the threat of defederating from them again.
dbzer0 is currently gathering allies from smaller lemmy and piefed instances to agree to collectively defed from lemmy.world if they follow through on defederating anarchist.nexus again, because this should have been something discussed, not done in the dark at the whim of a single person.