Comment 15 for bug 1871543

I can reliably reproduce this:
1. Inside several aarch64 systemd-machined containers (with PrivateUsers=0 in nspawn conf) with focal and running Gnome Shell session (accessed via TigerVNC server). Hosts in NanoPC-T4.
2. On one bare metal NanoPC-T4 host with focal, running Gnome Shell Wayland session. No container/virtualization stuff, only bare metal.

Symptoms looks the same?

~$ sudo /usr/libexec/rtkit-daemon --stderr
rtkit-daemon[5786]: Successfully called chroot.
rtkit-daemon[5786]: Successfully dropped privileges.
rtkit-daemon[5786]: Successfully limited resources.
rtkit-daemon[5786]: pthread_create failed: Resource temporarily unavailable
rtkit-daemon[5786]: Demoting known real-time threads.
rtkit-daemon[5786]: Demoted 0 threads.

With --no-drop-privileges it works:
~$ sudo /usr/libexec/rtkit-daemon --stderr --no-drop-privileges
rtkit-daemon[5781]: Successfully called chroot.
rtkit-daemon[5781]: Successfully limited resources.
rtkit-daemon[5781]: Running.
rtkit-daemon[5781]: Canary thread running.
rtkit-daemon[5781]: Watchdog thread running.

However, in both cases I have to use Armbian kernel.
For the record, on RPi3B running generic Ubuntu 20.04 aarch64 image (boot via UEFI) this issue is not reproducible.

I can help with further debug here, or my issue is different and I have to go to Armbian forum? In the former case what exactly I need to de to help debug this?