In Tabletop, the DM can adjust encounters if characters go above a certain level. Add a few more minions or something to correct. But, honestly, D&D is built so that even if you are a level higher or lower than expected, it shouldn't be game over.
That's not true so much for BG3. Facing the Gith at level 2 or 3 is suicide because the encounter is Deadly CR for level 4. Level 5 would still be a high CR. This also true for the Spider Matriarch and many of the late surface game encounters - like fighting 30 enemies in the goblin camp after you kill their leaders. Weren't they supposed to scatter once the leaders are dead? Great plan, Wyll.
Anyway, I'm not sure what the solution should be, really. Larian loves Deadly CR encounters, so that makes it difficult.
