In 5e, creatures get a new saving throw against most spells at the *end* of each of their turns. On a success, the spell's effect on them ends. Since it happens at the end of their turns, if they fail the initial save they're guaranteed to be confused for at least 1 turn.
BG3, however, has new saves happen at the *start* of creatures' turns. Thus, every creature gets 2 chances (effectively Advantage) to succeed on a spell before feeling its negative effects.
Additionally, there are various bugs in BG3 where failing the 2nd save STILL removes the condition from the creature, in what I assume is a "-1 x -1 = 1" situation. The game says "you failed, so toggle the confusion condition on your character" which toggles it from ON back to to OFF.
tl;dr: ST spells with durations in BG3 suck (except for maybe Hypnotic Pattern)
This is actually pretty important because a save at the start of the turn means you dont get to take actions on CC'ed mobs if they pass, whereas a save at the end means you at least get one more turn of hits until they succeed.
But I have 95% chance on holds on both my PC and Jaheira both in full caster DC gear which is very easy to do in act 3, and it even works on most bosses, you only need about 21-22 DC for this. Bosses still need heighten for 95% but regular mobs don't.
