Why do people say the 80s were conservative? The USSR still existed, and the left in the West was still actually the left rather than "capitalists who support gay marriage". The 90s were 100 times more conservative than the 80s, the 2000s even more so, and I'm not so convinced that on a worldwide scale the 2010s are not the most rightwing decade ever. (Although the left in many areas has supposedly "radicalized", that is turned into fanatics of Woke Capital.)
I'm not sure if I would agree that the left in the 1980s Western nations was all that "left" outside some unelectable Militant Tendency people who failed to have much impact. Plus even the USSR moved towards capitalism in this decade.
It was still more leftist than any later decade. China was still largely a socialist economy. There were leftist revolutionaries like Thomas Sankara.
Comparing it to the 70s - the decade when the Left was at the height of its global power - is wrong. Compared to later decades the 80s were pretty left.