There wasn't any real balance patch. Just people who have gotten much better at luring deer to improve early build orders. Like 3 years ago, you'd just assume 2x Boar + 8x sheep as your early food source. But today, people are adding 2x or even 3x deer to that.

As deer + boars collect food at the fastest rate, you can more consistently go up at lower villager counts. There's also much more precision: killing boars / deer / sheep under the town center more consistently today than before.

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TL;DR: Skill improved, people can do 18 pop today even though its always been possible. So people are just getting faster and more optimized.

The goal of the April patch was to make organ guns more of an anti-unit shotgun, and less of a wall destroyer. So you'll see fewer organ guns on Arena (one of the few maps that start off fully stone walled).