My biggest problem (although not okay either) is not with the stutter that sometimes occur when closing apps. Tbh, I’ve seen that with other Iphones too.
Rather the stutter disturbs me the most when scrolling, reading e.g. this thread. It is very annoying when you try reading something, and there is constant stutter.
But, as you said, it can be hard to spot. And at least for me, the intensity of the stutter differs to some degree, sometimes it is very evident, other times less so. This results in my hypothesis that a lot of people simply don’t notice the stutter.