The Browser Tester shuts down for no reason

Is there any reason why the tester which runs in the browser abruptly shuts down a few minutes after using another tab in the brower? Sometimes I use the tester in the brower for training and also for testing feature. It shuts down the brower tab it is running in a few minutes after I switch to another brower. Why does it not just remain open until I shut it down?

Best Regards

This is by design.
Inactive browser sessions are closed to release the resources on the server.

Use the tablet version of the tester if this behavior of the webtester presents an inconvenience.