It isn’t present on mobile (at least on iOS) unfortunately. I use it all the time on the web though, and it’s very useful.
And now it's gone on web this morning. I'm not sure if something in the conversation blocks it or if it's part of some A/B test.
My ChatGPT doesn't have a three dots menu on iOS or macOS.
Oof. I won't be using this. The implementation is terrible: just forks a new tab in my browser (at least on Firefox). I want a horizontally scrolling view, clickable highlights that specify my subconversational contextual focus.