Teamspeak crashes on startup, won't open [pipewire-pulse]

I am using Arch Linux with Pipewire (version 0.3.17) as a PulseAudio/Jack replacement.

$ pactl info
...
Server Name: PulseAudio (on PipeWire 0.3.17)
...

To reproduce: Install Teamspeak with flatpak install flathub com.teamspeak.TeamSpeak, and then run with flatpak run com.teamspeak.TeamSpeak. Teamspeak crashes on startup, and doesn't open.

$ flatpak run com.teamspeak.TeamSpeak
QCoreApplication::applicationDirPath: Please instantiate the QApplication object first
Qt: Session management error: None of the authentication protocols specified are supported
Crashdump ENABLED,  directory is: /home/user/.ts3client/crashdumps
DUMP defined! Dumpdir is: /home/user/.ts3client/crashdumps
2020-12-08 03:36:09.254583|INFO    |              |   |TeamSpeak Client 3.5.6 (2020-11-25 13:53:42)
2020-12-08 03:36:09.254727|INFO    |              |   |SystemInformation: Linux 5.9.12-97-tkg-cfs #1 TKG SMP PREEMPT Thu, 03 Dec 2020 00:56:54 +0000 x86_64 Binary: 64bit
2020-12-08 03:36:09.254817|INFO    |              |   |Using hardware aes
2020-12-08 03:36:09.409020|DEBUG   |PulseAudio    |   |connected to pulse audio server - 
/app/extra/ts3client_runscript.sh: line 47:     6 Segmentation fault      (core dumped) ./ts3client_linux_amd64 $@

This is also reproducible with the teamspeak3 package from the Arch repositories. It also has identical behaviour and log:

$ /usr/bin/teamspeak3
QCoreApplication::applicationDirPath: Please instantiate the QApplication object first
Crashdump ENABLED,  directory is: /home/user/.ts3client/crashdumps
DUMP defined! Dumpdir is: /home/user/.ts3client/crashdumps
2020-12-08 03:45:01.932785|INFO    |              |   |TeamSpeak Client 3.5.6 (2020-11-25 13:53:42)
2020-12-08 03:45:01.932844|INFO    |              |   |SystemInformation: Linux 5.9.12-97-tkg-cfs #1 TKG SMP PREEMPT Thu, 03 Dec 2020 00:56:54 +0000 x86_64 Binary: 64bit
2020-12-08 03:45:01.932868|INFO    |              |   |Using hardware aes
2020-12-08 03:45:01.945357|DEBUG   |PulseAudio    |   |connected to pulse audio server - 
/usr/bin/teamspeak3: line 47:  6350 Segmentation fault      (core dumped) ./ts3client_linux_amd64 -platform xcb $@

I figured that this should be reported here instead of as a bug report to Teamspeak. Pipewire-pulse is supposed to be API compatible with PulseAudio, so something is clearly not being mimicked correctly here.