Too many enemies spawn at once in the procgen dungeons, from them all popping into existence the instant an enemy dies to the framerate chugging whenever they do spawn. It would be nice to have some dots on the mini-map of remaining enemies because some don't aggro or chase you.
When bosses goes off screen it's difficult to fire at them, some piece of UI exclusive to bosses that clamps to the edge of the screen would be great. Also enemies still find their way into boss rooms when I run past them on respawn. You should just kill them all when I enter a boss room. There's also hardly any time to pick up a dead party member during a boss fight since the majority of them just keep attacking and dodging for even a second cuts the progress down to half.
It can be overwhelming to have a ton of useless loot in your inventory, a way to delete and filter low level items would be great. Nioh 2 has a pretty robust filtering system where you can set it to not even pick up items below a certain rarity. Sometimes I find it annoying to read and compare items for all 6 slots for all 3 characters, Final Fantasy 6 has a great Optimize button that just equips the strongest equipment at once, you could set it to just equip items of the highest rarity so the player only has to think of the whatever leftover item they know they'd prefer to have equipped.