So Miraculous Ladybug is premised on, exactly three characters beside Marinette canonically know Marinette is Ladybug (Adrien is not among them), and exactly three characters beside Adrien canonically know Adrien is Chat Noir (Marinette is not among them). Thus, between these two characters there are four different ships assuming neither knows the other's identity, plus the ship where they both know they both know both identities, plus variations on those themes depending on who knows what. There are ship wars. AO3 used to have four / tags for these characters and now has one.

How might this play into "don't change the pairing"?

Because I can see convincing arguments for both "if it's Ladrien without Marichat, it needs to stay Ladrien without Marichat, because Ladrien and Marichat are totally different dynamics" and "it's the same two characters so the difference between Ladrien and Marichat is immaterial". Going with the former answer could impact remixes of esp the "happens before remixee" and "happens after remixee" varieties in ways the latter answer can't, because a favorite trope in ML fandom is Identity Reveal. If it's important that a remix of a pre-reveal Adrienette-only fic stay Adrienette-only, then the remix must also be pre-reveal.

I'm hoping for "it's the same AO3-canonical pairing tag regardless", but I don't know.