Environment

WordPress: 6.4.2
Create Block Theme: 1.13.8

Details

From the Create Block Theme panel of the site editor, enter any text in the subfolder and clone the theme.

The theme will then be activated automatically, but if you try to remove the theme after it has been deactivated, an error will occur.

I tested the following flow.

1. select Create Block in the Create Block Theme panel in the site editor
2. Fill in the required information and click Clone Theme.

3. The cloned theme will be activated automatically. We can see a message "Theme cloned successfully. The editor will now reload."
4. Activate another block theme (disable the cloned theme)
5. Delete the disabled cloned theme from Theme in Appearance

6. Error message is displayed and cannot delete. We can see a message "Deletion failed: The requested theme does not exist.".

Inside of wp-content/themes/ is like this. Didn't remove subfolder and cloned theme folder.

Of course, this can be handled by accessing the Themes folder and deleting the corresponding folder manually, but this is inconvenient.