So, like, I left for a year, then came back like a month ago, and I have no idea what this meta is, so if you could, please try to explain this to me.
AD champions are now the dominant because something to do with true damage, but actual ADCs aren't viable anymore for some reason. Bruisers are now the new ADCs, and mages have all but been deleted from the game and are only occasionally seen as either support, or taking the place of where an ADC should be. Control mages, mainly Zyra and Morgana, have now taken over support, while tank supports, with an exception to Braum and Taric, are now no longer viable along with ADCs. Also, for some reason we have assassins for support now?
That's about everything I know about the current meta so far.