Ah interesting, thanks for the fast replies!In the case of the Switch, your UniqueID is banned on Nintendo's server (and maybe console side, not sure). The UniqueID is verified at the factory, so you can't just replace it with garbage and get back online. A donor ID does work, but is just ban bait fot Ninty.
As for you what you experience, that depends on the ban. It can range from no online game access to no online access at all.

We have a banning thread for a reason.I was just wondering what exactly happens when a console gets banned.