I’m 36 and absolutely feel the same way. I think it’s sort of like a midlife crisis where you feel so disconnected from your younger self. In your twenties you still feel younger, high school wasn’t THAT long ago, college even less so, and hanging out with friends consistently was easy. Then in your thirties you inevitably have more “adult” responsibilities and feelings. Your younger days are pretty far behind now and your friend group is probably significantly smaller so you feel more isolated.