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
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.