Clerics are underpowered in BG3? Is that so? I'm no DnD/ BG1,2 player and have no experience, but I'm quite satisfied with what I get. Clerics could need a better cantrip perhaps, but the need to use a weapon often instead also gives a nice special touch, so I don't see much urge for changes. Later levels of course I cannot speak of.
Compared to what they should be the vast majority of spells and features are in the game. But alot of the subclasses are missing. The phB alone already has 8 if memory serves. Some, like the war domain cleric turn the cleric into something closer to a fighter then the current domains that we have in the game.
Honestly though, cleric is 1 of the few classes that you could fill an entire party with (provided the run different domains) and that party would work just fine for like 99% of the game. Its a very versatile class. This whole 'cleric is underpowered' sentiment is abit of an overreaction I feel...