https://autovista24.autovistagroup.com/news/what-were-best-s... says, for the first half of 2025:

  Best-selling BEVs in China
  January to June 2025

  Geely Geome Xingyuan     205,091
  BYD Seagull              174,912
  Tesla Model Y            171,491

and

  Tesla’s quarterly delivery boost meant its June results
  propelled the Model Y into third, from fifth in May

⇒ I doubt the Tesla model Y is the best seller in China.