Ekko does have counterplay

Ekko has specific paths that can play around him. 1) Burst 2) Poke 3)Trading

1. Burst Ekko's damage gets more and more dangerous and reliable the longer he stays in a fight. If you use burst very quickly after he joins in a fight he will be forced into ulting to escape well simultaneously making it dangerous for him to land his damage from his other spells. So don't try to fight skirmishes against him because he will probably win.

2. Poke Alot of Ekko's strength comes from his ability to go into a fight and then heal an insane amount instantly. However poke is damage that he doesn't want to use his ult on so it weakens him and makes his engages much much more risky. On a side note grievous wounds before his ult is good.

3. Trading This is much harder to do because he does have a shield but you just need to trade in such a way that he doesn't get to use it to protect his health bar. Playing passive when his w is up or baiting it out are both viable strategies. Once his shield is down it makes it a lot riskier for him to engage or trade which is good for you.

Ekko might be overtuned but first wait a bit to see how people handle him once people are familiar to playing against him because he does have very clear weaknesses. He is dangerous in extended fights and bad in short fights. SO keep that in mind the next time you play against Ekko and maybe things will go better for you.