First, double-check your config. Sometimes, even a small mistake in SCRAM authentication can cause issues. Since Java is able to fetch the topic list but Python isn’t, it’s likely either a configuration issue or the Python Kafka client isn’t connecting properly.

If you're running this inside an EC2 instance within the same VPC, you might not even need authentication. Try removing security_protocol="SASL_SSL" and see if it works without it.

Also, check your SSL config—maybe there's a problem with TLS or missing certificates? Try running it with security_protocol="SASL_PLAINTEXT" or PLAINTEXT just to see if the connection works.

Reference: AWS MSK Authentication Guide