could someone tell me how is yasuo a fair champ?

Then poke him with q only then use ur combo.

Literally q him once, pop off his shield and he just gets obliterated. Hıs only source of defence is windall and without that he is extrememly vulnerable to poke damage. If he cant e q tornado someone in a tf he basically just stands in the backline doing nothing until someone engages. After he ults cc him and watch his hp bar deflate like a balloon. Also many yasuos have an incredibly inflated ego to the point where if they land a long range q once they'll instantly ult you to assert dominance. Try to use their mental state to bait them out of position.