From Mozilla link above: Since publication of the ESNI draft specification at the IETF, analysis has shown that encrypting only the SNI extension provides incom

From Mozilla link above: Since publication of the ESNI draft specification at the IETF, analysis has shown that encrypting only the SNI extension provides incomplete protection. As just one example: during session resumption, the Pre-Shared Key extension could, legally, contain a cleartext copy of exactly the same server name that is encrypted by ESNI. The ESNI approach would require an encrypted variant of every extension with potential privacy implications, and even that exposes the set of extensions advertised. Lastly, real-world use of ESNI has exposed interoperability and deployment challenges that prevented it from being enabled at a wider scale.