XQuartz setting default shell for xterm under Ventura

In a clean rebuild of Ventura, my default shell is

/bin/zsh

. For instance, that is what shows up in a Terminal.app terminal. If I start an xterm (launched from XQuartz 2.8.4), the shell shown in

$SHELL

is

/bin/sh

(& in other tests, see Comments). The xterm should be using my default shell, but can't seem to make that happen. I did notice that

read org.xquartz.X11 login_shell

shows

/bin/sh

. However, I changed that to zsh with a

write

, restarted the computer, and there was no change in behavior. Edit, more info: Setting the XQuartz app_to_run parameter to

$0

reports

-zsh

, but setting app_to_run to

produces an xterm running

. I'm so confused. Edit, even more info: I've pushed the problem back to the XQuartz starting context. The problem only occurs if XQuartz is started as a Login item, or if it is started with a launcher (I use Quicksilver) which itself was a Login item. So it appears that Mac Login items are not using the default shell. Can anyone else replicate?