We didn't have a cold war last 20 years, except some in the US still maintaining a cold war mentality.
Now another pole rises in China and so a return to a "cold war" like system is possible. Personally, I hope we can come to an arms control limitation with China. In 20-30 years, even force parity will be charity on their part.
That's solely because the USSR collapsed and Russia is only a regional power, not a superpower. Russia has a small, weak, backwards economy that is of modest global consequence. It severely limits their capabilities. Russia's position on the global stage is still eroding. Had the USSR somehow survived and continued to this day, the Cold War would not have ended. Putin as an authoritarian dictator-for-life is unable to push his view of how things should be, onto very much of the rest of the world. Putin is boxed in, contained, by Russia's various weaknesses.
The contrast could hardly be greater with China, which is clearly going to be far beyond anything the USSR ever accomplished in most every sense (from financial/economy to technology to military to global influence).
China under Xi has chosen an aggressive authoritarianism domestically and a so-called Wolf Warrior policy internationally. They continue to push forward ever faster in those directions, rather than turning back. The fundamentally conflicting world-views, democracy vs dictatorship, market economies vs arbitrary command economy, liberal vs regressive, human rights vs lack of human rights, is why we're entering cold war round two. China's position under Xi on nearly everything is fundamentally incompatible with the rest of the world continuing to make liberal progress. Something has to give when those two visions meet, and that thing will guarantee a new cold war that will split the planet in half.
Go down the long list of liberal ideas & topics, and look at where China stands, and then consider where the world should ideally stand. China stands opposite nearly every liberal idea you can name. There's your cold war, and nothing can stop it short of China resuming the brief period of modest liberalization they underwent before Xi took over - or the world giving up all the liberal progress it has made post WW2.