I would like ti know if this over treble feeling Is subjective
When it comes to treble or upper-midrange sensitivity and/or liking, it is always
subjective as per the individual. In general, individual preferences and liking will always be subjective. It all depends on what you like and how you like your gear to sound. What you might consider bright, someone else might consider sparkly and exciting. Same goes for upper-midrange ear/pinna gain. What one person might consider a shouty upper-midrange, could be strong, forward instrument definition for someone else. We all like different things and that is why there are so many brands in the world, with a variety of IEMs with different sound signatures, targeting different tastes and preferences. If everyone liked the exact same thing, it'd be such a boring world and companies would have no scope for experimentation or come up with new things. In fact, these many companies wouldn't even exist!
Haha.
Objectively, when it comes to talking about tuning or specific frequency regions with a reference in mind, it depends on the target curve you select as reference; Diffuse Field, Etymotic, Harman, etc, and how these IEMs translate compared to them. Of course, you don't necessarily have to judge or like IEMs solely on their ability to hit a target curve since fun tuned IEMs can be dam amazing and hell lotta fun too. Even though as an audio engineer, I really love and enjoy reference tuned headphones and IEMs, I quite dig and enjoy well done fun signatures too. Anyway, talking about S8F's 4k-10kHz response (what you're probably finding peaky) with target curves in reference, it is quite within the Harman 2019 IEM target, similarish to a tiny bit above the Diffuse Field target ( particularly 8-10kHz) and definitely north of neutral compared to Etymotic target. Now, a person liking one target curve over the other is again going to be a
subjective preference but that doesn't diminish objectivity they bring to the table or the research, high value and importance of these target curves in general.
Nevertheless, you're not alone in finding the S8F a little bright and intense. A lot of people do. I reviewed the
Fearless S8F (link) 2 years back and stated all of that but also how fun, interesting and intriguing a listen it is, not just for me personally but a lot of people.
My 2 cents... Cheers!