From https://www.openssl.org/docs/man3.0/man7/migration_guide.html
Engines and "METHOD" APIs The refactoring to support Providers conflicts internally with the APIs used to support engines, including the ENGINE API and any function that creates or modifies custom "METHODS" (for example [EVP_MD_meth_new(3)](http://man.he.net/man3/EVP_MD_meth_new), [EVP_CIPHER_meth_new(3)](http://man.he.net/man3/EVP_CIPHER_meth_new), [EVP_PKEY_meth_new(3)](http://man.he.net/man3/EVP_PKEY_meth_new), [RSA_meth_new(3)](http://man.he.net/man3/RSA_meth_new), [EC_KEY_METHOD_new(3)](http://man.he.net/man3/EC_KEY_METHOD_new), etc.). These functions are being deprecated in OpenSSL 3.0, and users of these APIs should know that their use can likely bypass provider selection and configuration, with unintended consequences. This is particularly relevant for applications written to use the OpenSSL 3.0 FIPS module, as detailed below. Authors and maintainers of external engines are strongly encouraged to refactor their code transforming engines into providers using the new Provider API and avoiding deprecated methods.
related to: https://github.com/kamailio/kamailio/commit/394878313770a3b8b57a346a0a323eff... all ENGINE_* warnings