Description of problem:
After I've switched from one user to another one, the sound doesn't work. The sound applet doesn't seem to find any sound device, and the multimedia keys don't work. Logging off and returning back to the initial user, the sound doesn't work any more either, the device is still visible in the sound applet but the sound can't be modified.

Version-Release number of selected component (if applicable):
$ rpm -qa | grep -e pipewire -e xfce
libxfce4util-4.16.0-3.fc34.x86_64
libxfce4ui-4.16.0-3.fc34.x86_64
xfce4-panel-4.16.2-1.fc34.x86_64
xfce4-settings-4.16.0-3.fc34.x86_64
xfce4-screenshooter-1.9.8-2.fc34.x86_64
xfce-polkit-0.3-6.fc34.x86_64
im-chooser-xfce-1.7.3-5.fc34.x86_64
imsettings-xfce-1.8.2-3.fc34.x86_64
xfce4-session-4.16.0-2.fc34.x86_64
xfce4-screensaver-4.16.0-2.fc34.x86_64
xfce4-terminal-0.8.10-2.fc34.x86_64
xfce4-about-4.16.0-3.fc34.x86_64
xfce4-power-manager-4.16.0-2.fc34.x86_64
xfce4-pulseaudio-plugin-0.4.3-5.fc34.x86_64
xfce4-screenshooter-plugin-1.9.8-2.fc34.x86_64
xfce4-datetime-plugin-0.8.1-2.fc34.x86_64
xfce4-places-plugin-1.8.1-5.fc34.x86_64
xfce4-appfinder-4.16.1-2.fc34.x86_64
gtk-xfce-engine-3.2.0-13.fc34.x86_64
xfce4-taskmanager-1.4.2-1.fc34.x86_64
f31-backgrounds-extras-xfce-31.0.4-4.fc34.noarch
pipewire-0.3.26-4.fc34.x86_64
pipewire-libs-0.3.26-4.fc34.x86_64
pipewire-alsa-0.3.26-4.fc34.x86_64
pipewire-gstreamer-0.3.26-4.fc34.x86_64
pipewire-jack-audio-connection-kit-0.3.26-4.fc34.x86_64
pipewire-pulseaudio-0.3.26-4.fc34.x86_64
pipewire-utils-0.3.26-4.fc34.x86_64

How reproducible:
Always

Steps to Reproduce:
1. login as one user -> sound works
2. screenlock
3. switch to another user

Actual results:
Sound doesn't work, coredump in journalctl --user of the 2nd user (see below)

Expected results:
Sound works and one can switch from one user to the next (it used to work under F33)

Additional info:
May 03 21:06:36 mylaptop systemd[2014]: Stopped target Bluetooth.
May 03 21:06:36 mylaptop systemd[2014]: Reached target Bluetooth.
May 03 21:07:00 mylaptop pipewire-media-session[2352]: native: listen(): Address already in use
May 03 21:07:00 mylaptop pipewire[2352]: 'spa_bt_device_find(monitor, object_path) == NULL' failed at ../spa/plugins/bluez5/bluez5-dbus.c:3145 interface_added()
May 03 21:07:00 mylaptop imsettings-daemon[2054]: [ 1620068820.207361]: IMSettings-Daemon[2054]: WARNING **: Child process exited with code 1
May 03 21:07:00 mylaptop systemd-coredump[21527]: Process 2352 (pipewire-media-) of user 1001 dumped core.
                                                    
                                                    Stack trace of thread 2352:
                                                    #0  0x00007fbc1faad292 raise (libc.so.6 + 0x3d292)
                                                    #1  0x00007fbc1fa968a4 abort (libc.so.6 + 0x268a4)
                                                    #2  0x00007fbc1dfd6a50 interfaces_added (libspa-bluez5.so + 0x37a50)
                                                    #3  0x00007fbc1dfd6f86 get_managed_objects_reply (libspa-bluez5.so + 0x37f86)
                                                    #4  0x00007fbc1fe3cb0a complete_pending_call_and_unlock.lto_priv.0 (libdbus-1.so.3 + 0x16b0a)
                                                    #5  0x00007fbc1fe40fec dbus_connection_dispatch (libdbus-1.so.3 + 0x1afec)
                                                    #6  0x00007fbc1f2c256a dispatch_cb (libspa-dbus.so + 0x156a)
                                                    #7  0x00007fbc1f2d439b loop_iterate (libspa-support.so + 0x839b)
                                                    #8  0x00007fbc1febdd7b pw_main_loop_run (libpipewire-0.3.so.0 + 0x45d7b)
                                                    #9  0x000055f0d0760bf6 main (pipewire-media-session + 0xebf6)
                                                    #10 0x00007fbc1fa97b75 __libc_start_main (libc.so.6 + 0x27b75)
                                                    #11 0x000055f0d076121e _start (pipewire-media-session + 0xf21e)
                                                    
                                                    Stack trace of thread 2358:
                                                    #0  0x00007fbc1fb709ee epoll_wait (libc.so.6 + 0x1009ee)
                                                    #1  0x00007fbc1f2dd898 impl_pollfd_wait (libspa-support.so + 0x11898)
                                                    #2  0x00007fbc1f2d4304 loop_iterate (libspa-support.so + 0x8304)
                                                    #3  0x00007fbc1fea5e73 do_loop (libpipewire-0.3.so.0 + 0x2de73)
                                                    #4  0x00007fbc1fc48299 start_thread (libpthread.so.0 + 0x9299)
                                                    #5  0x00007fbc1fb706a3 __clone (libc.so.6 + 0x1006a3)
May 03 21:07:00 mylaptop systemd[2014]: Started dbus-:1.26-org.a11y.atspi.Registry.
May 03 21:07:00 mylaptop systemd[2014]: Started dbus-:1.2-org.xfce.ScreenSaver.
May 03 21:07:00 mylaptop at-spi2-registryd[21705]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
May 03 21:07:02 mylaptop systemd[2014]: Started dbus-:1.2-org.freedesktop.thumbnails.Thumbnailer1.
May 03 21:07:03 mylaptop pkexec[21883]: pam_unix(polkit-1:session): session opened for user root(uid=0) by (uid=1001)
May 03 21:07:07 mylaptop systemd[2014]: Started dbus-:1.2-org.freedesktop.secrets.
May 03 21:07:09 mylaptop systemd[2014]: run-user-988.mount: Deactivated successfully.
May 03 21:07:16 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:12 error:19 (Operation not supported)
May 03 21:07:16 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:13 error:19 (Operation not supported)
May 03 21:07:16 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:14 error:19 (Operation not supported)
May 03 21:07:16 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:15 error:19 (Operation not supported)
May 03 21:09:30 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:12 error:19 (Operation not supported)
May 03 21:09:30 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:13 error:19 (Operation not supported)
May 03 21:09:30 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:14 error:19 (Operation not supported)
May 03 21:09:30 mylaptop pipewire-pulse[2328]: pulse-server 0x5643e8aae5e0: [PulseAudio-Lautstärkeregler] ERROR command:87 (EXTENSION) tag:15 error:19 (Operation not supported)
May 03 21:12:02 mylaptop systemd[2014]: dbus-:1.2-org.freedesktop.thumbnails.Thumbnailer1: Deactivated successfully.
May 03 21:15:03 mylaptop at-spi2-registryd[21705]: X connection to :1 broken (explicit kill or server shutdown).
May 03 21:15:03 mylaptop systemd[2014]: dbus-:1.26-org.a11y.atspi.Registry: Main process exited, code=exited, status=1/FAILURE
May 03 21:15:03 mylaptop systemd[2014]: dbus-:1.26-org.a11y.atspi.Registry: Failed with result 'exit-code'.
May 03 21:15:03 mylaptop systemd[2014]: dbus-:1.2-org.xfce.ScreenSaver: Main process exited, code=exited, status=1/FAILURE
May 03 21:15:03 mylaptop systemd[2014]: dbus-:1.2-org.xfce.ScreenSaver: Failed with result 'exit-code'.
May 03 21:15:03 mylaptop systemd[2014]: dbus-:1.2-org.xfce.ScreenSaver: Consumed 1.813s CPU time.
May 03 21:15:03 mylaptop pkexec[22217]: anita: Error executing command as another user: Not authorized [USER=root] [TTY=unknown] [CWD=/] [COMMAND=/usr/sbin/xfpm-power-backlight-helper --set-brightness-switch 0]
May 03 21:15:04 mylaptop systemd[2014]: dbus-:1.2-org.freedesktop.secrets: Deactivated successfully.