The Mauler seem to be taking extra stagger after the latest patch. See video where I perma-stagger a Mauler by spamming light attacks on combat axe with T5 Headtaker.
Not sure if it’s just the Mauler or all enemies are taking more stagger damage as I can as stagger a Dreg Rager out of their super-armor combo by spamming light attacks in addition to knocking them onto the ground in the Psykanium with their AI turned off.