Redis 6 adds support for TLS, but LuckPerms fails to load with it (need to set SSL to true in jedis connections), I had to switch to plugin messaging temporarily. This will also require updating jedis dependency to 3.3.0

Additional info :
Redis needs the client (luckperms) to give a certificate and you need to trust the server certificate.

You can add the server certificate to your java using :
keytool -import -alias CERTALIASYOUWANT -keystore $JAVA_HOME/lib/security/cacerts -storepass KEYSTORE_PASSWORD -file redis_ca.pem
(default KEYSTORE_PASSWORD in java is changeit)

And you can specify your own certificat by running the server java with parameters :
java -Djavax.net.ssl.keyStore=./KEYSTORE_FILE.p12 -Djavax.net.ssl.keyStorePassword=KEYSTORE_PASSWORD -jar server.jar

More information here : https://stackoverflow.com/questions/5871279/ssl-and-cert-keystore

(This might be obvious for many, but due to the pain I had to find this, I don't see why not help the next people)

You'll need to add the ssl property to your config:

redis:
  enabled: true
  address: localhost
  password: 'example'
  ssl: true