@Gabriel Ferreira In SignalR Serverless mode, the group membership is maintained as long as the connection is active. If the connection is lost and re-established, the group membership is not preserved, and the connection needs to rejoin the group. However, if the connection is still active, the group membership is maintained even if the application is restarted.
Regarding the expiration time of the User-Group mapping membership, there is no expiration time in SignalR Serverless mode. The membership is maintained as long as the connection is active.
The documentation you mentioned is for SignalR in general, and it may not apply to SignalR Serverless mode. In SignalR Serverless mode, the group membership is maintained as long as the connection is active, and there is no need to re-add the User to the Group again.