Defender says my hosting is configured incorrectly

Defender is presenting the security following tweak as of two days ago:

Often servers are incorrectly configured, and can allow an attacker to get access to sensitive files like your config, .htaccess and backup files. Hackers can grab these files and use them to gain access to your website or database.

I’m hosting with WPMUdev so I hope my hosting is configured correctly. Just Puzzled. How should I proceed…