So after my signature verification fix, the browser still crashed twitht he following errors:

Tor Browser Launcher
By Micah Lee, licensed under MIT
version 0.3.2
https://github.com/micahflee/torbrowser-launcher
Downloading Tor Browser for the first time.
Downloading https://aus1.torproject.org/torbrowser/update_3/release/Linux_x86_64-gcc3/x/en-US
Latest version: 9.5.4
Downloading https://dist.torproject.org/torbrowser/9.5.4/tor-browser-linux64-9.5.4_en-US.tar.xz.asc
Downloading https://dist.torproject.org/torbrowser/9.5.4/tor-browser-linux64-9.5.4_en-US.tar.xz
Verifying Signature
Extracting tor-browser-linux64-9.5.4_en-US.tar.xz
Running /home/nuc/.local/share/torbrowser/tbb/x86_64/tor-browser_de/start-tor-browser.desktop
Traceback (most recent call last):
File "/usr/lib/python3.8/site-packages/torbrowser_launcher/launcher.py", line 397, in success
self.run_task()
File "/usr/lib/python3.8/site-packages/torbrowser_launcher/launcher.py", line 266, in run_task
self.run()
File "/usr/lib/python3.8/site-packages/torbrowser_launcher/launcher.py", line 427, in run
if not self.check_min_version():
File "/usr/lib/python3.8/site-packages/torbrowser_launcher/launcher.py", line 415, in check_min_version
for line in open(self.common.paths['tbb']['changelog'],'rb').readlines():
FileNotFoundError: [Errno 2] Datei oder Verzeichnis nicht gefunden: '/home/nuc/.local/share/torbrowser/tbb/x86_64/tor-browser_de/Browser/TorBrowser/Docs/ChangeLog.txt'
fish: “torbrowser-launcher” terminated by signal SIGABRT (Abbruch)


I managed to get it running by installing and then uninstalling the AUR version (tor-browser).

So I cannot reproduce the issue anymore, but there is something wrong.