Despite the impressive things that web apps and web browsers can do now, much of the web and the internet in general still work with decades of technology. This applies not only to applications such as mail or IRC but also to technologies such as TCP / IP, HTTP (excluding S) and FTP. These will not be retired soon, at least without breaking the internet, but some, such as FTP, are starting to disappear, to the point where Mozilla has decided to begin removing it from the Firefox web browser.
FTP, short for File Transfer Protocol, has long been available as the standard protocol for transferring files from one computer to another over a network. It is one of those old technology parts of the wider internet and was not exactly designed for the needs and, most importantly for the dangers of today.
Last year, Mozilla announced its decision to finally remove built-in support for FTP. This followed Google's lead in removing the same functionality from Chrome as it did last April 82. Mozilla begins this journey with the release of Firefox 88 but will not completely eliminate FTP functionality until version 90.
This practically means that users will not be able to browse FTP directories as they have been able to for years. Some add-ons may also crash, especially when FTP is completely removed from the browser. You will need to use a dedicated FTP client for this purpose, but as mentioned recently, some of them have made some questionable changes.
Firefox 88 was released a few days earlier than planned on Android. The update has some bug fixes for the mobile browser version, but as Android Police noted, it does not bring new add-ons to the critically acclaimed and extremely short list of extensions based on Mozilla's new rendering engine.
Source of information: slashgear.com