I got banned from Reddit while I was on a work trip to the USA. Hadn't posted in over a year at the time. I'm absolutely mystified as to why.
They refer you to the content policy but they won't tell you which post might violate it. I asked a few times what it was that caused the ban, but they either just referred to the content policy or once they said "Repeated violations".
I actually requested my user data so I could stick up my complete post history publicly and see if anyone else could figure it out. My username was / is sirdeadbeef on reddit.
I haven't put any work into displaying them nicely, this is the format you get them in if you request your data:
