I suspect your shadowban is related to how new your account was, its de-facto low reputation and its even lower reputation due heavily downvoted comments you made: https://news.ycombinator.com/threads?id=turdistheword
Accounts with a high comment flag rate are timed out. New accounts with a sufficiently high comment flag rate are permanently timed out.
Accounts likely operated by known trolls are manually shadowbanned.
Sadly, there are "known bad" IPs--hell even entire blocks.
I'm relatively new here and, heretofore, had no idea "browsing dead" was even an option.