It’s a design flaw, not user error. And no domes have been cut off; XP-L HI emitters don’t have a dome. The problem is that the optic was not designed for XP-L HI — it rides too deep and slices into the emitters. Basically, the lights were broken at the factory by tightening the bezel too far.
This issue is known by Fireflies, and it is the reason why the XP-L HI version is no longer available. It has been replaced with XP-G3 and SST20 instead, because they fit into the optic better.