First I would like to point out that there are many western centric academic organizations, even ones that trend against China/pro Occidentalism, that have come to the same conclusion.

The idea that China is not authoritarian is blatantly false, however the positive perception of their governance, by the common folk, is not really a surprise, and it shouldn't be. For 50 years the material conditions of the average person in China have been improving. The public largely values stability, safety, the ability to move around the country, healthcare as a human right, home ownership as a human right, and food/water as a human right. All of these things China has. Their medical system is not free at the point of service, however it is very low cost as they are tightly controlled on how much they can charge for medicine (though there is a rising wave of bad medical debt there that is a topic of discussion and looks like they may become a fully socialized system in the coming decades to stop this). They are unable to own property as a financial investment, just for use in their lifetime, this leads to home ownership being something you can accomplish even in the most expensive urban centers, with 70% (and growing) of millennials owning their home. Prices around food, like medicine, are tightly regulated, they do not allow for the profit margins seen in places like the US.

When asked about long term positions, like the presidency, most Chinese will point to how they have a lot of choice, and votes, for local representation, and also point to how China is far more able to plan for long term goals by having the highest strata of their government there for the long term. They will also point to the laws regarding the need for rigorous civil service metrics amongst government officials, and how this leads goals the public largely values over most things. They will also point out how politically stagnant a lot of the west is because of the dead lock created by the short term focus of our government.

While we decline in QOL metrics, the Chinese see inclines. While out infrastructure is crumbling, as politicians withhold money to fix, and upgrade it, to score political points, they have developed one of the best public transportation systems on Earth, expanded their communications systems in incomparable ways, and are on a fast path to being the most advanced energy, and food, producers on Earth. While we can not afford housing due to private equity practices, most of their citizens buy their own homes. These things are equated to freedom, and positive feelings about their government.