That's kind hard to pin down. Khrushchev did mass amnesty to clear them; Brezhnev went right back to mass imprisonments; Gorbachev loosened things up.
Again, Navalny died in one of the more notorious Gulag sites; it never completely went away.
Again, Navalny died in one of the more notorious Gulag sites; it never completely went away.
The argument that gulags were essential is "when their use was drastically reduced, the Soviet Union declined". I think that's overly focused on one element - the collapse had many causes - but easing up on dissidents is likely to have played at least a part. I'm not surprised today's neo-Stalinists yearn for a return to the system.