Looking at the (short!) list of defederated instances, I tried looking through this magazine to read about what caused some of the defederation actions -- unfortunately it looks like some of that information might've been lost in the mbin migration and subsequent cleanup?
Given the list's short length, would it be possible to create and vaguely maintain a list with a brief reason for the defederation and whether each is expected to be a temporary or permanent situation? There's a couple of communities I was interested in on lemmy.ml which for better or worse don't seem to have a great in-fediverse alternative.
Most were suspended for child porn at various points - though I think it was not necessarily something they condone, but lemmy has damn near no ability to moderate or remove images once they land on a server