Yes, speaking in regards to the economic concept, more than half of China is still a third world country.

They have about 900 million people living on $7 or less per day. Half a billion people there are living on $3-$4 or less per day. Of the poorest two billion people on earth, more than 1/3 are in China. Their income numbers for the bottom 50% compare with the poorest nations on earth.

Granted, the problem with China is it possesses the most inequality of any major nation between the top 50% and the bottom 50%, due to the vast rural vs east coast gap in incomes. The nation with the second most billionaires, that has half a billion people living as subsistence farmers.

First/second/third world is not an economic concept. Both Namibia and the Philippines are first world countries. Both Switzerland and Sweden (and Austria too) are third world countries. China -- by the very definition of the first/second/third world -- is a second world country.

Please use the proper terms: developed and developing.

Please accept that definitions change over time, and it doesn't help if you're complaining about your definition being stuck in the past. The global narrative moves on regardless.