Odd problem with window geometry

[Al Eisner <eisner@slac.stanford.edu>]

I have had a consistent problem in starting up emacs on a Rocky 9 Linux
platform.  (I have no control over the machine, but it appears to be
using emacs-27.2.)  If I specify window size (with either -g or --geometry)
on the command line, I first see a window of appropriate size (which
changes when I change the values), but then as initialization completes
it collapses to a window with only 3 or 4 lines; there is also a small
change in width.  This happens whether or not I have a .emacs file.  (I
have no other initializtion file.)  I have longed used emacs on both
Redhat=6 Linix and Linux OS-7, with no such problem, but I think the
emacs version there was 25.  In case it matters, I use XMing as my X
server, but that is unchanged from my usage on the other platforms.

Does this behavior ring a bell with anyone?  I must be missing something.
Thanks.