XOrg cannot switch to VT virtual terminal : unsupported maximum keycode

[Hanasaki Jiji]

^Alt-4,5,6 etc result in the following in syslog.  The screen "seems" to
lock (become unresponsive) however the ^Alt-#ofXorgScreen does bring back
the GUI.   Note that this is a custom 5.x kernel.  Booting the bundled
Debian Testing Bullseye 5.10.x kernel works fine on the exact same system.
(Asus VivoBook Ryzen 3700u)

Thus, I suspect it's something in the custom kernel build.  Thoughts on
what the cause could be, diagnosis and/or fix?

TIA

Feb 10 18:25:29 debian gnome-shell[3681]: The XKEYBOARD keymap compiler
(xkbcomp) reports:
Feb 10 18:25:29 debian gnome-shell[3681]: > Warning:          Unsupported
maximum keycode 569, clipping.
Feb 10 18:25:29 debian gnome-shell[3681]: >                   X11 cannot
support keycodes above 255.
Feb 10 18:25:29 debian gnome-shell[3681]: Errors from xkbcomp are not fatal
to the X server
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