As others have said, the first one is not a bug because Yasuo's Q is technically an auto attack and anything that stops auto attacks will make the skill do no damage, give no Q stacks, and refund the Cd. The second one is just a very odd occasion where the knockup area is very slightly larger than the damage AOE of Q, by about 25 units or so. You will notice it only happens when you hit someone with the very edge of a spinning Q.
I was honestly hoping that you would talk about the most crippling of Yasuo bugs, where he sometimes simply cannot auto attack after using skills. You just stand there, unable to auto, usually for only around half a second but sometimes even up to 2 seconds of being completely unable to auto. Not to mention that his wind wall is also a buggy piece of shit, particularly against TF's Wild Cards.