Samsung’s 120Hz mode is a quite power-hungry mode that’s seemingly not as optimised as one would hope it to be. While the performance and fluidity it brings is outstanding, expect on average a 20-25% power hit on your battery life depending on use-cases. People using their phones on higher brightness levels will see less of a percentage degradation, while those who prefer lower brightness levels will see larger degradations, due to the increased baseline power consumption of the phones.
Secondly, the Exynos 990 variants of the S20s aren't looking very well against the Snapdragon 865 variants. While last year Samsung had managed to showcase rough equivalence between the Exynos 9820 and Snapdragon 855 variants when it came to battery life, this year, the gap in battery life between the two is again very noticeable. We’ll be re-running some of the battery tests presented here and hopefully, they’ll improve somewhat in their results, but the one thing that’s clear is that Samsung’s SoC and CPU cores are behind by some very significant margins.