As Hanno Böck noted in the recent Bulletproof TLS Newsletter, FTP Support in Firefox 90 has been removed. We’ve seen similar messaging from most major browser vendors over the last few years.
I’m going to make a bold prediction, and say in 10 years time we’ll be seeing the removal of (plain text) HTTP support as well. Regardless of internal or external networks (an out-dated concept aligned to the Crunch Shell of network security), the move to stronger security for all communications, backed by free TLS Certificate Authorities (such as Let’s Encrypt) means we should be doing end-to-end encryption for everything the common web browser fetches.
For some time, Firefox has had an HTTPS-only mode, with warnings when services try and dip back to unencrypted access. I’ve typically found this warning pops up when various link-shortening services are chained together, and I’m grateful for the awareness that a jump in that chain is poorly implemented.
In the meantime, the distribution of files using FTP needs to stop. If you run an FTP service then you need to think about transitioning to something that permits access using HTTPS as the transport protocol.
Another sunset in the circle of life of a protocol.