IIRC, it was around 2018, somebody made a post about the titled topic. Can't remember the exact assertion and can't find the post with CMF's search. I made a refutation back then.

Here's the latest figure of Chinese urban rapid rail system, aka metro, or mass rapid transit or mass transit railway or etc. At the end of 2020, total mileage reached 7545.6 km out of a total of 43 cities. The top ten are Shanghai (729.2km), Beijing (727 km), Chengdu (557.8km), Guangzhou (553.2 km), Shenzhen (422.6 km), Wuhan (409.1 km), Nanjing (394.7 km), Chongqing (343.3 km), Hangzhou (306.3 km), Qingdao (246 km).

In comparison, India has a total metro system length of 760.6 km of which 51.2% is in Dheli (389 km). In the previous post, the guy used Dheli as a showcase of India's large metro system. But in reality, Dheli would only ranked eighth in China. Metro in Shanghai or Beijing alone would almost be as large as the entire metro system in India.

To put in perspective, compare with two other cities Singapore (203 km) and Hong Kong (174.7 km), both just surpass Dalian at 16th place. And Taibei (152.9 km) just surpass Kunming at the 19th place.