Application Passwords is a new feature in WordPress version 5.6. It's used to make authenticated requests to various WordPress APIs. However, this feature can be utilized by bad guys to gain control of your website. Therefore, it's recommended to turn off this feature when you upgrade your website to WordPress 5.6.
WordPress 5.0 has just been released, however, not everyone loves the new block editor - Gutenberg. This article will guide you how to simply disable Gutenberg with just one line of code, no plugins needed.