China's use of SNI-based censorship is well-documented

For example, see

https://censorbib.nymity.ch/pdf/Niere2025a.pdf

China has blocked ESNI

https://gfw.report/blog/gfw_esni_blocking/en/

But SNI is not CH and ESNI is not ECH

Will China block ECH

ECH blocking has been detected in Russia

https://github.com/net4people/bbs/issues/417

According to Niere et al. (2025)

"Additionally, with the ECH extension not yet being widely used [17], [71] and focusing on privacy protection rather than censorship circumvention [60], it can be censored easily by blocking it entirely [14], [76]."

The paper describes various GFW bypass methods that currently work, including removing the SNI extension entirely

It does not mention anyone using ECH to bypass GFW

Perhaps it is too early to conclude "China blocks ECH" because ECH is not in widespread use

Yes, but SNI is not ECH.