wp_redirection_404 table has grown to 7GB

That table is from the redirection plugin, and isn’t a part of WordPress Core. Deleting it should have no ill effects as long as you disable the plugin too.

If you wish to continue using that plugin though, I recommend using the plugin authors support at https://wordpress.org/support/plugin/redirection/

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)