It's definitely an acronym that got popular in the last year or so, though I'm sure there are people out there who will pretend otherwise. I've been in the industry 15+ years now and never heard it before. Previously it was just UI, GUI, or CLI.

It's gotten more popular for sure, but it's definitely been around a long time. Even just on HN there have been conversation about gdb tui ever since I've been here (starting browsing HN around 2011). For anyone who works in embedded systems it's a very common term and has been since I got into it in 2008-ish. I would guess it was much more of a linux/unix user thing until recently though, so people on windows and mac probably rarely if ever intersected with the term, so that's definitely a change. Just my observations.

My friends and I have been actively in the "CLI/TUI" since middle school. Anyone tinkering on linux that used tiling window managers is already very familiar with the domain.

As someone who came up using Borland's Turbo Pascal, Turbo C, and Turbo Vision (their OOP UI framework), it was called CUI (character-based user interface) to distinguish from GUI, which became relevant as Windows became dominant.

I never heard "TUI" until the last few years, but it may be due to my background being Microsoft-oriented.

One of the only references I can find is the PC Magazine encyclopedia: https://www.pcmag.com/encyclopedia/term/cui