I do not see anything about this either, so I believe that it will be a “normal” mass at the closing of the Youth Synod. I think the sources you are seeing are probably just against the Norvus Ordo mass, which is understandable, but a far cry from the sky is falling. I don’t think anyone is fooling themselves for a second that Pope Francis would even consider celebrating an EF mass, but there’s enough dirt out there on Pope Francis that I don’t think we need to resort to conspiracy theories to attack him.
I think the worst thing we’ll see at the Youth Synod is some dancing, and if we’re lucky we might even avoid that.