It signals that now it is <too late> to complain about
release 21 bugs.
That is because we are getting close to pretesting Emacs 22.
Until 21 release, it was <too early> to do so.
Quite the contrary! That was the best time to report them. The whole
point of pretesting Emacs 21 was to fix its bugs before it was
released.
We continued fixing bugs in Emacs 21 for a while after it was
released. But now we would rather focus on fixing whatever bugs
remain in Emacs 22.
Do these problems still exist in the CVS sources which will become
Emacs 22? The basic idea of field handling is unchanged in Emacs 22,
but some details may be different, so I would really appreciate your
checking and reporting _specific_ Emacs 22 problems now.