I just want to point out that despite their aesthetic similarities, mindflayers and great old ones don't Actually have all that much to do with each other in lore. As far as I understand at least.
I guess, a Netherbrain could be seen as an eldritch being, but yes, Great Old Ones are a whole different number ( Lovecraft and eldritch horror fan here).
I would have wished to have more interactions with Auntie Ethel as a feylock. You should have been able to see through her disguises sooner for example. A fiendlock should be able to readthe infernal on Astarions back ( hell, Well and Karlach should be able to do that) You get so much bonuses for other classes to solve a situation, but warlock has not much, not even a conversation with their patron or something like that.
