Problem: Larian has inflated means to gain Advantage (height / backstab), which only benefits the "hit" kind of spell. Advantage (or disadvantage) for you doesn't change an opponents saves. That's why it's more often lower in BG3.
Not only that they also halved enemy AC values to make missed attacks less common, but doubled HP values to keep average TTK the same. Spells that target saves get no benefit from the AC reduction but still have to deal with the increased HP thus are much worse relative to attack save spells than they should be.