https://www.mediawiki.org/wiki/Wikidata_Query_Service/User_Manual/SPARQL_Federation_endpoints lists the AGROVOC endpoint as http://agrovoc.uniroma2.it:3030/agrovoc/sparql

Using that in a query does not work (example), it gives a 403 Forbidden error.

AGROVOC still has a SPARQL service, at https://agrovoc.uniroma2.it/sparql/ and looking at the network requests, it appears to be posting the query to the same URL. That URL is not allowed though (example) so it seems the endpoint URL needs updating.

(@EBernhardson I've added you to the ticket because you've handled some of the federation requests in the past - if there's a better person to ping about things like this, please let us know)