4. That they'll tweak the xp so perfectly that you have to do almost every quest/kill everything/steal everything to stay at an appropriate level, like they did with DOS2.
But it was opposite for dos2 and i worried about it in bg3. You can leave act2 way earlier than clear the whole island (you just need 3 source points). So they design difficulty, keeping in mind that someone really may leave it with unveiled areas\unfinished quests. But if you cleared everything (which is normal as for me, why skip something in new game), you 1-2 levels above of your enemy on act2, and you will stay with this advantage to the end of game. Which ruins any challenge\difficult, and game start being easy from this moment. There special mods on steam, which raise enemy levels to your\reduce xp to prevent this. But first playthrough was ruined.
So i hope they change it in BG3. I don't wanna skip Hag or druid rescue fights to make my underdark fight interesting.