If you search for the dealer manuals (or youtube it, I'm sure), you can adjust the clutch fairly easily (but need a tiny open-ended wrench...a 3.5/4mm, I think). It's stiffer than SRAM, when it's new. If you're ever in the area, you can even beg a tiny bit of Nexus grease from me for the clutch, in a tiny ziplock baggy.
like
@alex_k was showing in his pics, part of the master cylinder piston is simply too big, dimensionally. The new levers don't have that problem--which SRAM
pays shops to fix, as in, costs you nothing. Most bigger shops keep a warranty kit in stock, so your downtime is minimal. If your Level/Guide levers don't have a dimple (small countersink) above the hose port (pull back the rubber cover, it should be under the vertical part), they will even be replaced if they're not experiencing symptoms. I know there are shops out there that grumble about warranty work, but this is one of those cases (and Shimano's long-standing crank recall) where they should be knocking each other over to fix your problem.