Command substitution does not work with 'C-h k'.:

0. emacs -Q

1. C-x r l

2. C-h k m

I now see a buffer with this text:

  Mark bookmark on this line to be displayed by \<bookmark-bmenu-mode-map>\[bookmark-bmenu-select].

I expect to see:

  Mark bookmark on this line to be displayed by v.

This works as expected in Emacs 27.2.  I suspect this is a recent regression.

In GNU Emacs 29.0.50 (build 1, x86_64-apple-darwin17.7.0, NS appkit-1561.61 Version 10.13.6 (Build 17G14042))
 of 2022-06-20 built on SK-MacBook-Pro
Repository revision: 162576b634c7a586bd93a904a97aa16790282984
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1561
System Description:  Mac OS X 10.13.6

Configured using:
 'configure --with-native-compilation'

Configured features:
ACL GIF GLIB GMP GNUTLS JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP
NOTIFY KQUEUE NS PDUMPER PNG RSVG SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS WEBP XIM ZLIB

Important settings:
  value of $LC_CTYPE: UTF-8
  locale-coding-system: utf-8-unix