Basically, I'm not saying China will break the deal or not. I'am saying there is lot of hype about the deal.
CHina is more interested to appease US than to challenge US trough a real CSP with Iran.
Because in the past, China choose to throw Iran under the bus to appease US.
The talks on the deal with Iran begin since 2016 but nothing really concrete came out of it.
Was there a deal that China broke?
Anyway, since 2016, there has been quite a hectic new development between China and USA. Did you notice? Trade war leading to the Phase One deal, war on Huawei, US interference on Hong Kong and now Tiktok. Can you see the new calculus for China? Can you see that the past does not apply as much to China now?
Also, read up the perspective of this Iranian, Dr Fariborz Saremi, regarding the deal: