At least the following breaking change has not been documented. There is also a configuration that can be used to restore the previous behavior.

https://github.com/apache/activemq-artemis/blob/2.19.0/docs/user-manual/en/versions.md#upgrading-from-older-versions

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Due to ARTEMIS-3141, ARTEMIS-3128, & ARTEMIS-3175 the data returned for any "list" or "browse" management method which return message data, including those exposed via the web console, will have their return data truncated by default. This is done to avoid adverse conditions with large volumes of message data which could potentially negatively impact broker stability. The management-message-attribute-size-limit address-setting controls this behavior. If you wish to restore the previous (and potentially dangerous behavior) then you can specify -1 for this. It is 256 by default.

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