Not really, it's just a different story you get to know him through. The first time he appears in Remake, Cloud is having a massive PTSD flashback to a burning town, and then you see that Cloud has a raging hateboner against this ghost that he's obsessed with and sees everywhere, mistaking his sick neighbour for him and trying to murder him on sight. Until he shows up for real and he's involved with those weird shadows that few people can see and he acts ultra criptic and he makes no sense. It doesn't expect the player to know him, you just see Cloud's PTSD through his eyes, it's a madness and an obsession that's just hurting his head, it doesn't matter if you know him or not. Beyond that, it's part 1 of a trilogy, you're expected to wait for the next 2 parts to learn more about him and why Cloud hates him. Even at the beginning of Rebirth, he's the mysterious ghost whispering lies in Cloud's ears, making him doubt reality and go full "lalala you're not real" PTSD paranoia. People who know the OG, and people who don't, see his presence very differently.

It's not that you meet Sephiroth early and you're supposed to know who he is, it's that Cloud is crazy and you're supposed to doubt him. That gets stronger and stronger in Rebirth - you'll definitely start part 3 with Barret, Tifa, Yuffie convinced that Cloud is completely gone and lost, Barret's getting ready to take Old Yeller down, he's just waiting for Tifa to give up. I think that's a much stronger story today.