A new GPG signing key is used for the Jenkins long term support package repositories. Follow the instructions in the upgrade guide to install the new public key on your computer.
Adjust WebSocket idle timeout to 60 seconds by default, to avoid "WebSocketTimeoutException: Connection Idle Timeout" issues.
(issue 69955)
Restore the redirect destination of the pluginManager/installNecessaryPlugins API endpoint.
(issue 70599)