None of the players in the JCPOA negotiated in good faith.
Iran's continued support for Assad, the Houthis, Hezbollah (especially after their massacre of Syrian Sunnis in 2013 which lead to Jabhat Al-Nusra), and their backing of Nouri Al-Maliki's sectarian government leading to Iraq collapsing into civil war again showed Iran was negotiating with the Obama administration in bad faith.
Similarly, Russia and China's continued support for Iran's ballistics missiles program and other dual use technologies showed that Russia+China as guarunteers wouldn't end well.
There's a reason why the French - one of the guarunteers of the JCPOA - expanded their own offensive intelligence capacity in Tehran, unless you think the DGSE are American (ha)
We would have been in the same position today if Harris was president as well.