Those creatures can OS anyone and many other can OS unadvertised weaker characters.
Gnolls archers : 3 * 1D8+3 - average damages 22.5/turn.
I think redcap and other underdark creatures are also very powerfull. And obviously the gith patrol.
Keep in mind we're level 4 and we haven't met ANY really hard bosses...
I guess there are more insta kill in BG3 than in any other D&D games. Hopefully rez scrolls are cheap so it just doesn't matter but if perma death was something in BG3 and if a rez scroll was not so cheap... I guess It would be an issue way more than in the old games.