The default/fips provider RSA implementations support a new padding mode called RSA_PKCS1_WITH_TLS_PADDING. This has not been added to the legacy RSA EVP_PKEY_METHOD. However libssl now requires this padding mode to be supported. This means that any custom EVP_PKEY_METHOD for RSA that an app creates that wraps the standard EVP_PKEY_METHOD (such as is done in OpenSSL's daysnc engine) cannot be used in libssl.

This is the cause of the "unsupported padding mode" errors seen by @beldmit in #16734.

Should we attempt to fix this?