The quiet but ever-present whisper of "this place is not for you, you are not welcome here"

A lot of that can be helped by design, but a lot is purely cultural, and driven by perceptions of what others think - or what we believe they think. In Japan for example I always saw loads of people eating out alone in restaurants, it's just a normal thing to do. But in the west less so. Like the societal perception of the whole point of eating out is to do it with someone. Not just because you want some restaurant food.

So a lot can be overcome just by learning to not give a fuck.

It does give a peek into how other groups must feel though, like those with physical disabilities, as if the world is hostile by design. Or even worse, just hostile by omission because nobody remembered to think about you. And it doesn't need to be. But it is.