Samsung has been promising that for almost 8 years now. For some reason they absolutely cannot figure out how to design a proper high end SoC. I'm not familiar with the design of exynos chips but I don't understand how they barely do better than Mediatek. They have control over the entire design of their devices and should have performances that is closer to Apple than it is to low/mid-end off the shelf designs.

Based on what I've read it seems to me that the gap has become worth over the years... The last time I remember reading that the exynos was competitive was around the Galaxy S6 so 2015

The S6 was clearly much better Exynos than Snapdragon. They were competitive for a few years more after.

That was because the s6 exynos was to first mobile cpu with 14nm and the equivalent snapdragon (810) was a particularly bad SoC. To the point where it was outperformed by previous gen snapdragons. So yes Exynos was competitive then, but mostly because the competition had an exceptionally bad year.