BG3 just needed more time to cook unfortunately. The endings all suck, not because they are bad endings it's because they don't exist. It just ends suddenly. There's a massive hole of missing content right at the end and it's not hard to write, everyone knows what they want to happen with their party and maybe a bittersweet twist. Act 3 just really starts to break down part way through it, despite it being quite beautiful of an area. You can tell content was hacked out of it, there's weird missing chunks and it doesn't play like Acts 1 or 2 at all
Larian has a history of doing that, so I don't trust them to finish the game even if they were given more time. They probably would've made Act 1 and 2 even bigger instead.