Mind if I add on here? Some of these may not be exactly QoL.
11. During long games where I'm (shockingly) at peace with the AI players, it will often be the case that treaties will expire and there isn't a cue which tells me that I can renew them.
12. Sometimes when I'm browsing the tech tree I wonder 'why is this going to take so long?' and it would be helpful to indicate things like: high base research cost for that tech, low base research output. low research spending. This will remind me to look into those things.
13. The description or behaviour of the Sentry order is incorrect. It currently reactivates the ship or fleet when any foreign unit moves into range, instead of any enemy, by which I assume an enemy is someone that you're at war with.
14. The AI players seem to ignore the presence of the Peacekeepers when deciding to go to war. In the late stages of the game, Peacekeepers don't seem to have much of an effect on the well-armed empires.
15. I might get a popup about the Dread Lords being re-awakened, but there isn't any indication of what happens to them after I make my choice.
16. After successfully resolving a crisis, I don't seem to get a crisis manager to add to my government. Ever.
17. The Precursor relics are apparently defended by 'Pirate Attackers' but those enemies don't look like any pirates I ever saw.
18. Things like Birthing Subsidies or Military Subsidies still appear on the tech tree but can't be used as social projects (possibly because of mechanics changes in expansions).
19. The reward from Ship Graveyards can scale up technologically depending on how far on you are in the game, but the pirates defending them don't.
20. Some AI players complain about my military buildup without taking into account the other (AI) players who already have a considerable military buildup. Indeed, they will later open a channel and warn me that another player has amassed a large military.