It's complicated.

Reddit doesn't seem to ban an IP specifically, but they have ways of figuring out if accounts are associated. For instance, I was permanently banned for suggesting arson as a way of dealing with nazis moving in down the street. (I guess Reddit thinks that this is "encouraging violence", as if Nazis were human?). I always use a VPN. When I changed my location and logged in to an alternate account, that account got banned also. I made an account from a different computer a few days later, also with a VPN, and that account was banned as well; I had previously logged into my 1st account from that computer.

So I think that there's some kind of digital fingerprinting going on. I should have fingerprinting blocked on my computer, but it's still happening, somehow; there must be some kind of hardware configuration information that it's able to scrape that gives it a high enough degree of certainty that I'm me.. The only solution that I was able to come up with--I have not actually tried this--was replacing my computer entirely, and then creating a new account.

EDIT: I'm curious to see what would happen if I tried to log into my banned account from my wife's laptop. She has a reddit account; would they see me using her laptop as proof that her real account is one of my alternate accounts? IDK.