I think the most incredible thing is that baseline at level 1 the Sting gives the Unconscious condition on a plain DC 12 Con save, which is like a 35% chance every single turn without taking any of your action economy to give something the Unconscious condition and take it out of the fight. It only gets better with Investment of the Chain Master. It is basically a cantrip that gives the Unconscious condition. Before it needed an attack roll, a saving throw, and fail by 5 or more on the save to give this condition, and now it is simply a save.

we have had that since Tasha's the fun part is putting the Eldritch adept feat on a character with Pact of the chain. anyone can pull this off with either casting and a feat or two feats then there is the warlock that can do it

I just noticed something as I have a player who tried to use this exploit in game, and considering, that truthfully it could be OP, (Think solo mobs, bosses, etc.) I had to investigate further. Using the Pseudodragon is valid. However, here are the RAW: Additionally, when you take the Attack action, you can forgo one of your own attacks to allow your familiar to make one of its own "ATTACKS" (This is the key bit everyone seems to be missing) to allow your familiar to make one attack of its own with it's reaction. Look at the stat block, the sting is not an attack, it is an ability. Under multiattack it clearly states "The pseudodragon makes two Bite attacks." It does not list Sting as an attack, and also RAW, since the sting requires a saving throw it is an ability, not an attack.

Another thing - since your Bonus Action is free if the Pseudodragon is using Sting on its turn, you can use the Bonus Action built into the Find Familiar spell to benefit from its Blindsight.

I think it's also worth considering that when Sting was still an attack in 2014, and you had Investment, you could have it Sting twice a round. Admittedly, it wasn't a great option with the attack needing to hit and the target needing to fail the save and by 5 or more to make it unconscious. With Sting getting reworked, I have to think that it's intended to prevent two Stings in a round. Though, I'm open to there being oversight of it consequently not needing a Warlock's command at all to Sting.

Find Familiar spell gives you telepathy with any familiar, hence these still have it when used as a familiar.