Hi Luke,
Thank you for writing this bug report !, that said it is best to use GitHub to report them.
There is already an existing issue for PHP 8.4 deprecations: https://github.com/phpmyadmin/phpmyadmin/issues/19404#issuecomment-273307674... You can add "error_reporting = E_ALL & ~E_DEPRECATED" to the php ini file to avoid the headers issue (https://github.com/phpmyadmin/phpmyadmin/issues/19404#issuecomment-260839687...)
-- William Desportes