WordPress.org (the official maintainer of WordPress and the main repository of WordPress plugins) has removed a plugin called “Contact Form DB” from their database. This has had the effect of automatically removing this plugin from all WordPress websites that used it. Now, this plugin being gone might not effect your website in any way, but in at least one case that we know of it has broken important functionality.
This plugin is no longer in the wp.org repository, but the author now supports it here: https://cfdbplugin.com/. There are a number of reasons that plugins leave the repository, and you can see https://wordpress.org/plugins/search/contact+form+database/ for other plugins on wp.org that do the same thing or similar things.