Very soon after the program started, due to the emergence of the Cold War, the western powers and the United States in particular began to lose interest in the program, somewhat mirroring the Reverse Course in American-occupied Japan. Denazification was carried out in an increasingly lenient and lukewarm way until being officially abolished in 1951. The American government soon came to view the program as ineffective and counterproductive. Additionally, the program was highly unpopular in West Germany, where many Nazis maintained positions of power. Denazification was opposed by the new West German government of Konrad Adenauer, who declared that ending the process was necessary for West German rearmament.
While I’m not overly educated in the history of denazification in East Germany, I know that at least later, it was more of a proclamation than something actually happening. That’s why so many neo-nazis “suddenly appeared” in the supposedly nazi-free zone after the unification of the germanies.
Supported by the fascists in the west that had never gone away, the unified right made quick progress in their organization.
One example I found is https://www.dw.com/en/book-claims-stasi-employed-nazis-as-spies/a-1760980, but I have seen other sources in the past too.