Samsung's Exynos SoCs aren't very popular in high-end smartphones because they offer less power. But even in mid-range devices, the in-house processors fall behind.
https://www.notebookcheck.net/Samsung-Exynos-Performance-problems-not-only-in-the-high-end.505074.0.html
This isn't something new. Every comments in gsmarena also trashing Samsung for seems to be unlimited supply of exynos 9611 in their middle range phones, while the other manufacturers has already moved to sd 720/730 or even above. Exynos 9611 is comparable to sd660/665/662/460 which nowadays occupies lower end of most smartphones. Even mediatek g85/90/95 are better than that in most scenarios.