people would think I'm mentally ill if I acted around them like I act around my closest friends so yeah I kinda do. I do heavily suspect I have mild autism though

To an extent, think work friends versus the kinda friends you meet at a concert, or at the gym. It's not necessarily a "different" personality as much as shifting behavior and topics a bit. In short, I'm gonna talk a little different around my young engineering friends vs the guys I've known since high school.

Different interfaces or speaking styles, maybe. Sometimes literally different languages

you even use the same name across friend groups!?

Everyone do . Not talking about friends group respectively but in a way people have different personalities with different people like do you act/say/do things the same way you do with your parents and teachers , colleagues and your boss , your girlfriend/boyfriend and your distant friends , your best friends and your distant cousins ? No we all have different personalities when we are with different people .

A little bit. Different groups might engage more with different aspects of my personality, so I find myself naturally emphasizing different parts of myself accordingly. Code switching isn't that unusual, I don't think.

While I can't speak from experience, I would imagine this isn't terribly uncommon for black people in America at least (and other people of color).

There's still a lot of systemic racism over here, so unfortunately sometimes you have to mask who you are just to approach being treated the same as white people.

You guys have friend groups?