I actually looked up the text in the AI Act:

"The obligations set out in paragraph 1, points (a) and (b), shall not apply to providers of AI models that are released under a free and open-source licence that allows for the access, usage, modification, and distribution of the model, and whose parameters, including the weights, the information on the model architecture, and the information on model usage, are made publicly available. 2This exception shall not apply to general-purpose AI models with systemic risks."

https://ai-act-law.eu/article/53/

The why is under:

https://ai-act-law.eu/recital/102/

So the chinese models aren't exactly open like in the EU wants them to be