Suggested Changes to Yasuo's Kit to Make Him More Fair Without Removing Anything From His Kit

Remove his shield passive and put it on his W as a passive Remove the shield's per level gains in exchange for gains per point into W and maybe a small bonus AD scaling so it's not abysmal until level 13 Max flow required to cast W and uses the flow charges If W feels weak, could lower the cooldown in exchange for lower duration in future patches

tl;dr: more counterplay to Yasuo, weaker early game defense for better late game defense

Without removing anything from the champion's kit, it gives clear counterplay options against Yasuo and makes him feel more fair to fight. The shield being on his W means that he won't have it until he levels his W, meaning typically it wouldn't be until level 3 he would have the shield and restricting Yasuo to having to take his W sooner than he would, potentially at level 2 against strong poke champions. It would also force him to take W at level 3 if he wants the shield instead of just leveling Q and E against champions that don't have anything to windwall. It also means that his very early game is weaker, making it so he's actually threatened by poke champions and can't get free trades in for the first few minion waves.

The shield being on W also means that it's going to be weaker until the late game where it, imo, only needs to be strong, helping Yasuo survive teamfights that he would otherwise typically pop like a balloon in. The small bonus AD would help scaling a little into mid game to match enemy damage but not negate half a spell rotation from a burst mage at level 9.

Having the windwall tied to flow would also help playing against Yasuo feel more fair for a few reasons. One, there's a requirement and a cost that isn't waiting for the next minion wave to use it again. Two, the Yasuo player has to choose whether the shield or the active is more beneficial to him when his flow is active, adding a layer of skill expression to the champion. Third, the opposing champion(s) could counter Yasuo's windwall by activating his shield and forcing him to wait until his flow is fully stacked again to cast it. On paper it may seem too weak but that means that any champion with burst negated by windwall have to auto attack or use a spell to remove the shield if they want to use their full burst, giving Yasuo time to get close to them and stack his Qs.

As for the fourth suggestion, it should be left out of the initial change and then looked at as a possible buff if Yasuo's W feels too weak. and even then the duration should be lowered for a lower cooldown because one windwall in a teamfight is enough, there shouldn't be two or more per teamfight unless it's dragged out and much longer than a normal teamfight.