The main rationale behind this change is consistency, because many of the new OpenSSL 3.0 types have an OSSL_ prefix, and OPENSSL_CTX is a notable exception. More details can be found in the description and thread of pull request #12621.
There was a discussion on openssl-committers and an initial poll on doodle about the favourite replacements for OPENSSL_CTX (https://doodle.com/poll/drku9ziwvkp6tw25). Matthias
