Specific companies policies might need to have a common home page set for all users and currently, a confluence user personal setting will overwrite the global home page as stated in the documentation.
Confluence admin should have a setting to "force" the global home page over user settings.
I could create this query that will show all users that have a home page set instead of using the global home page:
and this delete sql will remove their setting leaving only the global home page setting.
Remember, always perform a full backup of the database before performing any update or delete query on it.