i_am_sy That was a quick spot ... was just updating the OP in this thread to mark that change as done. Anyway:
Yes, because the Tags page is default now. Only the default home page has the hamburger menu currently.
We'll be taking a very long and hard look at the way that "<" button and the mobile hamburger menu works across all areas of the site (especially on mobile).
The Tags view as default is something we wanted for launch, as we have a lot of research that shows it's a significantly better "first visit" experience (and the majority of members who visit each day fall into this group). Now the bug that prevented us launching with it configured that way is resolved, we've made the change. I know it sucks given you've all got used to having the hamburger on the All Discussions page.