Usually, a genuine junior getting banned is permanent. That said, I was banned as a true junior and survived it. There is some discretion used in all bans except in very clear extreme breaking of the rules. As for getting junior'd, it's usually based solely around a thread creation or repeated thread creation issue, be it clickbaits, irrelevance, list threads, ignoring warnings, obnoxious or non-contributive, and so on. That can be permanent or temporary. As far as I've seen, a junior'd poster who is actually a long term member is less likely to be permabanned than true juniors.