You're welcome to join in, @garlictwist Queer used to be a word used to insult gay men in particular, but also lesbians. The LGB community responded by taking it up themselves and defusing the insult, in the same way that gender critical women have taken the insult 'terf' and now use it proudly. But for some LGB people and their families 'queer' is still a painful and damaging insult.
Some lesbian or gay or bi people sometimes call themselves Queer. That may be because they have some internalised homophobia and don't want to call themselves gay or lesbian or bisexual or homosexual. Being Queer is regarded as trendy, unlike the popular image of lesbians — short-haired, political, hairy, no fun, man-hating etc. I suspect, too, that some bisexual people call themselves Queer in order to avoid the stigma that's sometimes attached to them.
The majority of people who describe themselves as Queer, in my experience, are straight people who want to send a signal that they're different. Many of those I know are in straight relationships. They may be actively trying to subvert what they perceive as typical sex stereotypes — so perhaps the man stays at home and looks after the children while his wife goes out to work. Or some seem to use it to indicate that they follow a kink-based lifestyle: I knew one Queer couple who both wore things like studded necklets and leather cuffs to work until asked not to.
But the majority of Queer folk, ime, are just plain old ordinary straight people who want to feel as if they're edgy and interesting. I imagine a lot of them are the kind of people who don't feel they fit society's model of how we are supposed to be. Look around at the Queer people in your university. Many of them are the type of people who don't look like we're supposed to look in this FB and TikTok age. The fat ones, the goofy-looking ones, the plain ones, the misfits. (I speak as one of them, I'm not judging) Calling themselves Queer makes them feel special and different from those who conform.
When I was at university a number of my contemporaries liked to describe themselves as anarchists. Others were Goths. The difference is that anarchists and Goths didn't have powerful lobby groups like Stonewall arguing that they were special and needed special rights. And they weren't riding on the backs of a genuine, formerly persecuted minority (LGB people) for credibility.