I’m not, no. I understand that it’s possible for fluid additives to cause problems with seals and hence manufacturers get arsey about incorrect fluids being used but I’ve got no way to check whether a fluid is ‘real’ or not, like most people I just need to believe the label!
Epic do seem to claim it’s OE fluid in their blurb “You’ll get 100ml of stock 2.5wt Suspension Fluid with your bleed kit – no fear of compatibility issues or voiding your warranty.” Beyond that, all I know about them is they’ve been making good and well priced bleed kits for years now which have had subtle improvements recently and the stuff they say is Shimano or Magura oil respectively is the right colour… 😁