When the agent sends a reply and resolves or closes the ticket using the 'Send and set as resolved' or 'Send and set as closed' options, the page will be automatically redirected to the Ticket List View.
This is the default behavior of the system designed to help the agents to view the other tickets in their queue without any additional clicks.
If you do not want the page to be redirected to the Ticket List View upon closing the tickets, you can update the status of the ticket from the Ticket Properties section instead of using the 'Send and set as Resolved/Closed' options.