After upgrading to RabbitMQ version 3.13.x the RabbitMQ Management console shows Deprecated feature warnings in the RMQ UI Home Page. Here are some related screenshots from the RabbitMQ Management Console.
RabbitMQ Version 3.13.x
RabbitMQ 3.13 introduced a warning banner that appears when deprecated features are used. The Management UI also has a page that lists deprecated features and provides more information.
Please make sure not to use deprecated features in RabbitMQ version 3.13.x.
References
RabbitMQ 3.13: Classic Queues Changes
Workaround
How to get rid of deprecation warnings in RMQ UI/Landing Page #11978
How to list and enable feature flags in RabbitMQ?
Here are some ways to list and enable feature flags in RabbitMQ:
List feature flags: Use the CLI command rabbitmqctl list_feature_flags
Enable a feature flag: Use the CLI command rabbitmqctl enable_feature_flag <all | name>
List and enable feature flags from the Management plugin UI: Go to Admin > Feature flags