This is not fixed on the "EXPLAIN" page. (where queries are explained etc)
It's correctly fixed on overall_footer, simple_footer and the ACP footer.
By the way, this change causes all style authors to update their footer template again. (Because all use a custom footer)
In 3.0.11 the footer was changed to change the hardcoded "Powered by phpBB" text to a language string and now in 3.0.12 there's this useless change.