PSA: When Camille is knocked out of her ult, the zone disappears.
No, you cannot flash out. No you cannot jump/ult/dash/blink out.
But you can play

All these champions have effective methods of removing camille from the ult, thereby removing the lock-zone and freeing their teammate/themselves.
Complaining is easy. Thinking about counters is harder.
Edit: Thanks to a lot of people reminding me of champions I forgot to mention :-)

:^)