Hello @CarlWang
Thank you, it’s clearer now.
Because of unstable network conditions, which can lead to websocket disconnection, sometimes onlyoffice editor will not auto synchronize the content being edited to the document server
As far as I can see, a user should face reconnection scenario in such cases. The general information about these scenarios was described here: Errors when co-editing online (via Nextcloud): Cannot open files / Internet connection restored - #4 by Alexandre
The possible workaround solution seems to be similar as the one described there. Probably, if you catch the error event, it likely means that a user was disconnected and there might be an issue with unsaved changes: ONLYOFFICE Api Documentation - Config