Xsession hangs in sudo edubuntu-langpack-installer

After an upgrade from Ubuntu 20.04 to 22.04, the graphical login stopped working. The display manager did not show up anymore.

After some dpkg-reconfigure gdm3 and other things, that seems to work now again. However, now KDE/Plasma still does not seem to run properly.

Strangely, I don't see any ~/.xsession-errors, so not sure really how to even debug this?

I noticed that the startup command seems to be startplasma-x11. When I run this manually, i.e. interactively, I noticed that it hangs in a sudo? So what does it do when it is not interactively? Also hang in sudo? And indeed, I restarted gdm3 once more, and then I checked pstree -a, and I see:

  |-gdm3
  |   |-gdm-session-wor
  |   |   |-gdm-x-session --register-session --run-script /usr/bin/startplasma-x11
  |   |   |   |-Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -nolisten tcp -background none
 -noreset -keeptty...
  |   |   |   |   `-8*[{Xorg}]
  |   |   |   |-Xsession /etc/gdm3/Xsession /usr/bin/startplasma-x11
  |   |   |   |   `-sudo edubuntu-langpack-installer
  |   |   |   `-2*[{gdm-x-session}]
  |   |   `-2*[{gdm-session-wor}]
  |   `-2*[{gdm3}]

So, what the hell? It hangs there in sudo? This seems totally fucked up. Why is it even possible in this startup script that it hangs there? And why don't I have any logs about this?

How can I fix this now?

This seems to belong to edubuntu-live. Maybe I just uninstall this... Edit Unfortunately, this has no effect. It still hangs in the same sudo? Edit Ok, there was still the file /etc/X11/Xsession.d/51edubuntu_langpacks, which was not removed for some reason... After just deleting (renaming) this file, it seems works fine now.

A bit meta: This is the PC of my dad. He did the upgrade and complained that login was not working anymore. How should he ever have debugged and fixed that? This seems like a extremely serious issue, that there is a potential hang in the login due to some older package which installed sth stupid to Xsession.d. Also, it's not so easy to fix it for him remotely. I don't see his screen. I just see what processes are running, and I can see the logs. I.e. no logs here in this case. Or often not sure which logs to look at...