It went from "spend 20% on whatever project you find interesting!" to "spend UP TO 20% on a project your manager approves of and can defend from their manager, with routine reporting on the status, direction, and potential outcomes."
Employees went from wanting to work at Google for the "20% Time" to not using it because it was a huge hassle that could risk their career advancement, if your 20% time project didn't pan out. It went from a perk to a gamble almost overnight.
The result in the same either way though: Google stopped innovating.