> Many of those issues (e.g. Tibet) have been known for decades though. And yet up until the last few years, western governments had no problems at all doing business with China despite them. Only in the last few years did those issues suddenly become dealbreakers.
It wasn't sudden at all, but a long-discussed, ongoing issue of international relations: What to do if/when China's economy grows to the point of them becoming a major regional or global power (economy being the necessary component of national power, required for financial and military power).
Even 20 years ago, it was a problem for the future. China's GDP was low (but growing), the country was poor (in aggregate, it's still not at all wealthy on an individual level), and as a result, their military and diplomatic power was weak. Still, everyone could see the direction their power was heading. There were two poles of opinions:
1) Embrace China in the international order, share with them its benefits (e.g., the World Trade Organization), accomodate their power, and help them gradually reform and become a democratic country. This idea may seem insane in hindsight but before Xi Jinping, China was opening up. I remember reading (translations) from Chinese internet forums, which had a much richer, sophisticated discussion of democracy and human rights than what I read in the US - democratic reform was a serious topic and many top Chinese leaders supported it to varying degrees. Also, a democratic China would be a lasting foundation for world freedom, peace, and prosperity. Russia would be the only serious outsider.
2) Oppose China: This one is easy to understand, but don't let the simplicity and certainty draw you in. Opposing them will make them an enemy, no matter the nuances, a major threat and cost for generations. Also, we may not prevail in that confrontation: The concentration of economic activity and population in the world will be in East and South Asia, with China geographically in the center of it; imagine China trying to compete with the US for influence in North America. Also, military power depends mostly on economic capacity, and with 4 times the population of the uS, if China becomes even half as rich per capita then their economy will double the US's. The US has never had a foe anywhere near it in economic capacity. The US would be the underdog in the long term (without lots of allies).
Option #1 was attempted, even exhausted, for obvious reasons. Now China has grown to present an immediate, not a future, threat. And Xi Jinping has strongly embraced aggressive, nationalistic foriegn policy, including militarily threatening almost all their neighbors (Japan, Philippines, Vietnam, India) and Taiwan; seizing territory in the South China Sea; threatening other countries such as Australia and (economically) European countries; censoring any business that criticizes them; and transforming a reforming, opening country into a brutal dictatorship and cult of personality. As one example: Chinese leaders before Xi (and since Mao) served 10 year terms; Xi did away with that and has become a lifelong dictator, like Mao, Stalin, and others before him.
At this point, the options are to oppose them or surrender. The Trump administration certainly didn't help (and was a strategic disaster, because the US's only hope is to balance China's great mass with the alliances that Trump worked to destroy, and which depend on the US's reputation, which Trump also worked to ruin), but by then there was no option but to oppose the Chinese Communist Party.