Was the TLS Connection bug actually fixed in 18c,
TLS Connection causes javax.net.ssl.SSLHandshakeException: Tag mismatch! (Doc ID 2573358.1)
I have seen this issue on 19c as well, we were not able to make an SSL connection Key manager, Later, Oracle Support suggested disabling the JIT compile and it fixed the issue.
JAVA_JIT_ENABLED=FALSE