Failure after update of Emacs from 28.2 to 29.1

[yalfg]

I've been using magit (and then with-editor) with a custom installation of Emacs 28.2 (and earlier from 27.1) without problem. After an update of Emacs to 29.1, I have a warning on opening the magit status:

 ■  Warning (with-editor): Cannot determine a suitable Emacsclient

Determining an Emacsclient executable suitable for the
current Emacs instance failed.  For more information
please see https://github.com/magit/magit/wiki/Emacsclient.

Running with-editor-debug gives:

with-editor: /home/user/.emacs.d/elpa/with-editor-3.3.0/with-editor.el
emacs: /usr/local/bin/emacs-fsf (29.1)
system:
  system-type: gnu/linux
  system-configuration: x86_64-pc-linux-gnu
  system-configuration-options: --prefix=/usr/local/stow/emacs-29.1 --program-suffix=-fsf --with-json --with-tree-sitter --with-native-compilation --with-file-notification=yes --with-xwidgets 'CFLAGS=-O2 -march=native'
server:
  server-running-p: t
  server-process: nil
  server-use-tcp: nil
  server-name: server
  server-socket-dir: /run/user/1000/emacs
    server
  server-auth-dir: ~/.emacs.d/server/
    WARNING: not an accessible directory
with-editor-emacsclient-executable:
 value:   nil (nil)
 default: nil (nil)
 funcall: nil (nil)
path:
  $PATH: "/home/user/bin:/home/user/.cargo/bin:/usr/local/sbin:/usr/local/bin:/snap/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/games:/home/user/.local/bin"
  exec-path: (/home/user/bin /home/user/.cargo/bin /usr/local/sbin /usr/local/bin /snap/bin /usr/sbin /usr/bin /usr/games /usr/local/games /home/user/.local/bin /usr/local/stow/emacs-29.1/libexec/emacs/29.1/x86_64-pc-linux-gnu)
  with-editor-emacsclient-path:
    /usr/local/stow/emacs-fsf/bin (t)
      /usr/local/stow/emacs-fsf/bin/emacsclient-fsf (29.1)
    /home/user/bin (t)
      /home/user/bin/myemacsclient (nil)
    /home/user/.cargo/bin (t)
    /usr/local/sbin (t)
    /usr/local/bin (t)
      /usr/local/bin/emacsclient-fsf (29.1)
    /snap/bin (nil)
    /usr/sbin (t)
    /usr/bin (t)
      /usr/bin/emacsclient (28.2)
      /usr/bin/emacsclient.emacs (28.2)
    /usr/games (t)
    /usr/local/games (t)
    /home/user/.local/bin (t)
    /usr/local/stow/emacs-29.1/libexec/emacs/29.1/x86_64-pc-linux-gnu (t)

I'm not using TCP (local to a machine) so the lack of ~/.emacs.d/server/ shouldn't be a problem.

The proper emacsclient-fsf executable is found: this upstream, self compiled Emacs 29.1 is installed under /usr/local/stow/emacs-29.1 and linked under /usr/local/bin using stow. So this looks good.

A specific thing of my setup (maybe?) is that I'm running an Emacs server using systemd, but the issue is from a different Emacs instance. I prefer using an Emacs instance per project, and the systemd server is only there to support automation like hooking Firefox/Thunderbird to TB. Could this be an issue?

When running manually the correctly found emacsclient, it works fine and connect to the systemd background instance (as expected).

Thanks

[yalfg]

I forgot to mention: if I set with-editor-emacsclient-executable to this same emacsclient, it works fine.