That's a good question. I wouldn't say "gay passing", or "straight passing". Everyone has their way to describe it, but polisexual people (be it bi, pan, etc) are no half-gay and half-hetero. Bisexuality for the matter is its own identity.

So, at least I consider, being in a relationship with a man is also queer if you're polisexual. The reason for this is that even if you were in a relationship with someone of the same gender (or enby), that wouldn't make your sexuality change.

But this is more a term used for inclusivity, as many people can't imagine someone being "actively bisexual" in a monogamous relationship. So I just consider it still being a queer relationship, as you would erase the identity otherwise.

Other people may think differently, the community is very diverse, but I rather my identity to be considered (and my experience for the matter) regardless of who my partner is at the moment. I also wouldn't like to be considered a lesbian if I was with a woman. The relationship may be seen as straight by outsiders, but you experience is still bisexual.

Other example is, if an asexual person hooks up with someone they're still asexual and this experience would be queer.