WHY AM I LOSING WORK ON THE PAGES APP

You don't provide a backstory here, so the quickest way to lose work is to not manually save your document once in order to trigger autosave for future document changes. Quit Pages without saving a document and the content is lost forever.

Pages does not have an insert mode. If you select text and type something, the selected text will be replaced by what you type.

You cannot use the thumbnails in the default Pages word processing document layout to remove text on those thumbnail pages. If you try, you will wipe your document (as it warns). You must select the text on pages you wish to remove and use backspace to delete that content and page item.

If you attempt to double-click a Pages document in Windows, or on Google Drive, an attempt will be made to open its zip container and that destroys the document itself. This may be true on other non-Apple filesystems and Cloud solutions too.

Anything else?