If someone is 'cancelled' they may find it hard to get more work or their existing /previous work will no longer be sold / promoted.
Whether or not it is permanent I think depends on the severity of the issue that got them cancelled in the first place.
I don't like the term or the way 'cancelling' is used to try to ruin someone just because a minority don't agree with their views.
Having said that, where it has applied to a person who has committed serious sexual assaults or abuse, for instance, I would agree with the principle, but not the term 'cancelling'.