I just got my new Alcatel 3T which runs on Android 8.1 and I was unable to switch users from any of the screens. Even if I logged in as an admin - the only way I can do it is to go Settings-Users&Accounts-Users and choose user I want to use.
On the previous versions it was alway possible to swipe down quick access menu and switch user from there. But now there is no such option.
I checked out my phone too and I'm only seeing the option you've describe. I even checked in the "Edit" option to see if it's something you can add to the menu and I don't see there's an option. To me, this looks like a change made by the developers with the update.