I have the same issue. It is now far too easy to irretrievably delete pages / tabs when renaming them.
In the latest build, duplicate one of your tabs. Then start to rename it 'TEST tab 1', but before you press enter to commit the change, go back to change the name to 'tab 1', and press enter to commit the change.
You probably used the arrow keys to go back a few characters, then pressed the delete key and pressed enter. You were immediately prompted to delete the entire tab, with 'Delete' as the default option. This deletes the page irretrievably, with no 'undo'.
If you were trying to rename one of your key pages, you now have to reload an old version of your file, losing any work you've done.
It should not be so easy to make critical mistakes.