Part of it was that I grew up in a rural area with shoddy internet connection until I was fourteen and most of my online experiences in my youth tended to hew closer to Web 1.0 and early Web 1.5 until I moved to a more suburban locale shortly before starting high school.
When the iPhone debuted, I didn't have the money to afford one and I didn't own a smartphone until 2018 when my old flip phone finally crapped out on me.
I also didn't like a lot of the pop culture that my peers in high school were into. My music tastes hew closer to that of a Boomer or a Gen X'er, and I was the kind of guy who preferred The Lost Boys and Vampire: The Masquerade to Twilight (back when Twilight was still culturally relevant) and despised Harry Potter even before it became a Millennial SJW meme. The only things I shared in common with my peers were video games and anime, and even then there were often discrepancies between what I liked and what was popular.
I don't know why, but I don't connect as well with most Millennials compared to the Gen X'ers or older Zoomers that I know. Whether it's pop culture tastes or social and political issues, I really do feel like that tired meme of "being born in the wrong generation"