FIX: Tor debian repo OpenPGP signature verification failed: Signing key on A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89 is not bound

Fix:

In /etc/apt/sources.list.d/tor.repo, change the GPG url to:

/usr/share/keyrings/deb.torproject.org-keyring.gpg

My file now looks like:

#deb     [signed-by=/usr/share/keyrings/tor-archive-keyring.gpg] https://deb.torproject.org/torproject.org trixie main
#deb-src [signed-by=/usr/share/keyrings/tor-archive-keyring.gpg] https://deb.torproject.org/torproject.org trixie main
deb     [signed-by=/usr/share/keyrings/deb.torproject.org-keyring.gpg] https://deb.torproject.org/torproject.org trixie main
deb-src [signed-by=/usr/share/keyrings/deb.torproject.org-keyring.gpg] https://deb.torproject.org/torproject.org trixie main

Different option is to use a workaround.

Workaround NOT RECOMMENDED:

echo "APT::Key::GPGVCommand "1";" > /etc/apt/apt.conf.d/99-gpg

It’s not pretty.