CC is encoded in the vertical blanking interval, isn't it?

If you are watching a digital cable channel, or a broadcast of a
digital feed, then is it possible that the errors can result from the
CC information being decoded and encoded over and over?

I am assuming this because digital video does not concern itself with
any part of the signal that is outside the visible screen. So if the
signal is ever digital, the CC data has to be decoded, stored as part
of the digital stream, and then encoded again when it's translated back
to analog. It could happen at your digital cable receiver, and/or at
the cable station, and/or at a broadcast facility that's getting a
digital satellite feed.