When the new normalized term store is active for properties, the PrefetchingTermLookup obtained via SingleEntitySourceServices::getPrefetchingTermLookup has to use the current EntitySource (and can't just default to assuming the current wiki).
This will cause SingleEntitySourceServices::getPrefetchingTermLookup to break in federation scenarios, where the PrefetchingTermLookup needs to access other wikis' databases (like the commons federation).