Yup, it was a shift because unlimited vacation was from the boomer era where employers actually treated employees fairly well. Companies started realizing that all of the boomers who had been with the company for two or three decades all had like two years of vacation time saved up. And when that gets counted as a liability (because the employee can just fuck off and disappear for an extended period, while you keep paying them,) it was a big incentive for companies to begin limiting vacation.
Lots of the boomers were grandfathered in so they got to keep their vacation banked, mostly to avoid the “half of our entire staff just walked out of the all-hands meeting and put in for 2 years of vacation time each, because we announced we’d be clawing back any unused time at the end of the month” dilemma. But new hires get fucked with vacation time caps, and big limits on how much they can get paid out if they quit.