Evidently folks found Apple technical documentation for the Graphite Milanese Loop that noted the coating was PVD though that does not necessarily mean the watch uses PVD, as well.
The Gold Stainless was confirmed back in Series 4 to use a PVD coating and yet they don't mention that anymore in their tech documents. So it is possible Apple dropped mentioning the coating for the Stainless watches and only continues with the Space Black Titanium because it is a new(er) finish and in time, it too will also drop the (DLC) mention.
Personally, I'd argue that since Space Black Titanium is DLC and that finish sure looks similar to Graphite to me, I would assume Graphite is DLC for that reason, too.