As far as I know, when anyone gets banned from a jam it's ALWAYS permanent. This is actually quite unfair to people who haven't made mistakes big enough to deserve being kicked out so long. The amount of time away should depend on what someone did, so I want to see an option to decide how long someone is banned from a jam. For example, if someone is two weeks too young to join and won't leave, they can be banned for two weeks and come back when they're old enough. If someone drew all over the jam, maybe a few days, and longer than that next time if they don't learn their lesson. And if someone has caused unnecessary drama or harrassed people, at least a month.

Finally, if a banned person tries to enter a jam, the red message saying they're blocked should also say for long left, or the date they can come back.