I read somewhere, too long ago to remember where, that ideas about personal space are kind of geographically specific, at least in the US. The gist was that by a survey, people in the US Southeast required the most and the US Northeast the least. Other regions were somewhere in the middle. This was long before the Covid era made most of us sensitive to distance. (not everyone apparently!)
As a Southerner, I would have to agree with our results. I despise people getting in my face, and felt the same even BC19. Anyone who isn't my husband has no business getting closer to me than arms length, and that's pushing it.
A few days ago I was in a situation with several people I just met, scattered around a big area...volunteers at a thrift store, no customers, just sorting donations. I was talking to one woman and she kept getting closer, like 2 feet way and talking in my face. I would take a step back and instead of getting the hint, she would immediately take a step forward. This happened each time over at least 5 steps of me trying to put some distance between us! I gave up and went to another area as she seemed so oblivious.
So...what is a polite way to tell someone to get out of your face?! I wanted to say "just stay there, I'm backing up on purpose."! Possibly she was hard of hearing, I didn't want to be rude. (Southerner!) But I'm also not tolerant of that tiny amount of personal space that she seemed to find a-okay!