To be fair.
I don’t know if the passage of a handful of years would make a lot of people okay with seeing a demon in full demonic raiment strolling around the city and flaunting their demon-ness no matter what developments have happened with Velen welcoming in a faction of refugees.
I do have a Man’ari character or two. One of my most actively played characters right now is a demon, but they very much hide what they are and had to catch a Twisting Nether respawn one time due to being terminated by a Demon Hunter in the city, something that I welcomed and allowed OOC.
My characters have a variety of reactions to demons in the city, depending on their history and circumstances. Some are indifferent, some flip the heck out, some root for and defend them. There is a basic OOC courtesy that should be observed that goes both ways in an ideal situation, that you try and extend some grace for what people want to do.
On the anti-demon side, that looks like your character might make some comments or be upset, IC for them but generally only extending to the tip of their own nose, but you don’t godmode immediately try to murder someone without some OOC discussion and buy-in.
On the demon side, it’s maintaining an understanding that you’re playing a character that many other characters will have a negative reaction to if they’re playing their characters true to their history and personality, and if your interpretation is that a Man’ari would be able to show all signs and decor of still fully being a Legion devotee in the city without issue other people may disagree with that take. They shouldn’t be getting up in your business OOC about it, but also, the IC reaction of “WHAT? A DEMON? IN FRONT OF MY SALAD?” is valid even if it’s been a handful of years since the events of the Legion expansion. It’s not like demons stopped being a pain point after that.
A small faction of Eredar were welcomed back to the Exodar under heavy supervision. Whether they’ve had that supervision loosened enough to be running around to weekly markets and fountain-sitting is up to personal interpretation. But just because the Legion expansion ended doesn’t mean that all demons are cool guys now and the trappings of fel and the Legion would be chill in public, we’ll see this coming up in Midnight a bit more in Silvermoon at least where Warlocks who get too public with their continued use of fel and demons get executed, and that’s grudges held over from TBC. Sure, that’s over there, but it’s a sign of now not everyone in the world is on the “demons are fine now” page.
In the end, it’s up to each person what they want to play. Heck, I’m even fine if someone is like, “my character got isekai’d from the Hazbin Hotel universe and that’s why they’re a demon” or something. That’s their choice. But would my individual characters buy into it and play along? Likely not, even the demon would think they were weirdos.
It goes both ways. Everyone can make their own choices on how to interpret the lore and how closely they want to stick to it. But if you’re playing a public character in public, other characters in public will react in ways that are true to their characters too. Courtesy generally extends to not outright doing a murder, but a confrontation isn’t completely uncalled for depending on the circumstances. If you want to limit that you can specifically note that you’re not okay with conflict RP in your TRP or shoot them a polite OOC ask in whispers when it starts up and most people will observe it, but there’s really no way to ask people to not even have their characters make comments among themselves.
This guideline isn’t specific to demons, it goes for anything that people might have a problem with IC - Scarlets, Gnolls, all the varieties of Darkfallen, Horde characters visiting the city, historically whenever a new race gets added people crawl out of the woodwork to go around the city yelling “A PANDAREN ATE MY WHOLE FAMILY” and wear Pandaren skins or something. When your character is a walking posterboard for conflict, it’s very difficult to completely avoid it. But there should be courtesy and communication in both directions.