Yep. And the term you are looking for is - unironically - called "grandfathering."
If tomorrow, the City of Austin passes a regulation that as of 1/1/26 no new single-family home can be over 1-story tall, then any house that is not already over 1-story or has not applied for a permit under the current rules, cannot be more than 1-story tall. That is a legal framework that presently exists, is enforced nationwide, and does not result in any taking of property or other actionable harm to anyone.
If, on the other hand, the City of Austin passed that same regulation, but followed it with "and we're going to have to tear down 10% of the current 2-story houses," every owner of such a house picked for destruction would have a lay-down taking claim.
To bring the metaphor back home, actually firing or demoting people to make room for someone else would curl your hair and everyone else's, and for good reason. Changing the rules going forward, while it might FEEL unfair relatively speaking, is generally considered fair. Changing them retroactively, and actively taking away rights/things you have? Those are universally regarded as wrong and unfair. And as you seem to be hung up on the fact that Gen Z white males are pissed not because the playing field going forward doesn't favor them as much, but because those who played before aren't being penalized, then . . . yeah. My sympathy/empathy is low. That's just our monkey-banana brain at work. "No matter how many bananas I get, if some other monkey got more, I'm pissed."
But, again, y'all are missing the punch line that obliterates this conversation: white male grievance has WON. There will never be a better time to be a white male than in this new era. It is official US policy that they are the most favored demographic, and any time any white male loses at anything it is per se evidence of racial/gender discrimination and non-merit-based hiring etc. I have little sympathy for people who have captured all the levers of power, and are actively and proudly using them to favor one small group at the expense of literally everyone else.....and then bitch about how they haven't been able to....what, eliminate all non-white male competition from earth entirely? THEY'VE FUCKING WON. TAKE THE FUCKING W AND SHUT THE FUCK UP.