I have honestly no idea how do you missed news of BG3 entering early access if you were paying any degree of attention to anything gaming-related in that timeframe, because that thing didn't exactly go unnoticed.
Gaming sites talked about it extensively, youtube channels drummed the news, the game was a top seller on Steam since day one of EA, etc.
I mean, it's entirely reasonable to miss the news if you are not paying attentions to videogames in any way, shape or form, but in that case I'm not sure what could be suggested here that would work.
anyway, taking Larian's past M.O. as reference test phases probably won't be limited in any meaningful way. When the game will be ready for testing they will release and sell it publicly in Early Access, like they did for their past three titles (DOS 1, DOS 2 and BG3).
