Out of my last 20 ranked games, 12 have been tank ekko.

Probably both. Nerf base, nerf tank itemization, tweak his ratios.

Nerfing Sunfire Cape would go a long way to bringing down a lot of the damage-oriented pseudo-tanks that have been emerging in Solo Queue for the last few weeks. A lot of high-elo Youtubers and Streamers have been recommending a Sunfire+Iceborne build path because it is genuinely broken on certain champions. But this also presents the risk of damaging more balanced tank champions that build the same items.

That being said, the abusers should be the ones taking hits. Since Ekko just recently got buffed, I doubt it will happen to him. But Poppy is already being hit with consecutive nerfs that, quite frankly, do little to her overall impact. Maybe this next set will do the trick, but who knows?