If you pay me N extra hours, where N is less than the hours I worked on call then you stole from me. Plain and simple. This should be pursued by rabid labor lawyers and interest at the prevailing 30 year rate should accrue on those dollars hourly until they are paid back.
The problem is, of course, the law dictating “exempt workers” was written in a time where the only people that would be exempt were executives with actual million dollars golden parachutes. Now, white collar labor is almost universally exempt allowing the state sanctioned theft of millions of dollars a year by corporations who lobby to keep the laws the same, and promoted by “grind culture” immoral bottom-barrel blood-suckers like PagerDuty.
It’s bullshit. You’re suffering from Stockholm syndrome. You’ve somehow managed to say stealing from you is okay because they put some nominal amount of unrelated dollars in front of you.