a communist style of addressing people formally
It's weird. Polish is the only Slavic language (I think) that doesn't use wy (second person plural) as a polite form in the singular. I've heard it's sometimes used or even common in Eastern dialects but I can't say I've ever heard it.
In the PRL it was routinely used in the civil service, police (and I assume military) and of course among party members.
What's also unusual (not related to the PRL AFAIK) is the mixing of forms, that is using pan/pani with second person verbs, like "Co pan robisz?" or "Co pan robicie?"
I've also heard of using third person plural forms as a form of respect, a co-worker told me of an acquaintance who sometimes says things like "Ojciec kupili" (My father bought (it))