Whenever you are opening at Task or RITM it will show you a pop up message saying

“Leaving site? Changes you made may not be saved.”?

Note:-This message can vary according to the browser.

The system property glide.ui.dirty_form_support is creating this pop up message.

1.Go to System property

2.Serach for glide.ui.dirty_form_support.

3.Change the value to false.

It will stop showing you the pop up messgae.

These are some additional  documents that will give you better knowledge on this:

1.https://docs.servicenow.com/csh?topicname=t_EditingInForms.html&version=latest

Also I have attached a screenshot of the issue.