Dispelled, nr. Förbjuden, ja.
Hitta bekant varaktighet är momentant så det finns ingen permanent magisk effekt som ska tas bort. Den bekanta är inte skapad och upprätthålld av magi, du ändrar bara den för att få sin tjänst.
The spell harms, heals, creates, or alters a creature or an object in a way that can't be dispelled, because its magic exists only for an instant.
(PHB 203)
Den bekanta är , dock en varelse och kan därmed påverkas av stavar eller förmågor som påverkar varelser. Så ja, det kan vara förbjudet.
Banishment
You attempt to send one creature that you can see within range to another place of existence. The target must succeed on a Charisma saving throw or be banished.
If the target is native to the plane of existence you’re on, you banish the target to a harmless demiplane. While there, the target is incapacitated. The target remains there until the spell ends, at which point the target reappears in the space it left or in the nearest unoccupied space if that space is occupied.
If the target is native to a different plane of existence that the one you’re on, the target is banished with a faint popping noise, returning to its home plane. If the spell ends before 1 minute has passed, the target reappears in the space it left or in the nearest unoccupied space if that space is occupied. Otherwise, the target doesn’t return.
(PHP 217)