Band-Aid nerf for Yasuo until Riot manages to find a more permanent solution
Attack his base defensive stats and growth. I've noticed that in lane harass never really sticks to Yasuo. He either shields it, dodges it with Sweeping Blade, blocks it with Windwall, or heals it. If the enemy player manages to catch Yasuo in a situation where he doesn't have full flow AND can't Sweeping Blade to a minion to avoid the attack AND he doesn't block it with Windwall, then Yasuo should be severely punished for that. Poor Yasuo play simply is not punished enough, and I think this would be a step in the right direction to remedy that issue.
Another solution would be to nerf flow generation, but i prefer the former.