I posted an answer earlier and in a fit of flagrant spontaneous salutation I started it with "Hello from 2018" which was automatically removed when I posted.
I came on meta to find out more about this, and found the various posts about automatic content modification, which I'd never encountered before.
It's useful and strips out the noise, however it was confusing in UX terms, and if I wasn't already familiar with meta or realised that I had just added to the noise, I may have tried to edit it back in or other such nonsense.
There wasn't anything in the edit history or a notification to show that it had been edited or why.
I feel that there should be a notification to just say something like
"hey, we removed this, because it's noise, learn more on meta"
Or something to that effect. Maybe an entry in the edit history that can't be rolled back to (if that can be done).