I guess this isn't new but I was surprised to see the "Explorer Anthology 3" announcement. I thought the point of Explorer was supposed to be "cards that have been in Standard on Arena in the past". If they're releasing cards straight to Explorer, how is it not just "Second Historic"?
Keeping up with all the different Magic formats and what's legal in them is practically a full-time job. I'll bet there's someone at Scryfall who'd say that's not too far from the truth. I play Magic and read Magic news almost every day and apparently I still don't know.
(I went and looked it up: Explorer is different from Historic because it doesn't have Alchemy cards -- which is good -- and it's eventually supposed to sync up with Pioneer. I'd much rather see them advance that goal by releasing the old sets that are missing, and letting us draft them.)