[FC] ubuntu resolute: signatures couldn't be verified using "modernized sources"

[Felix Miata]

# cat /etc/apt/sources.list.d/fcl.sources
Types: deb
URIs: http://silk.apana.org.au/debian/
Suites: trixie
Components: main stable-dev unstable-dev
Signed-By: /etc/apt/keyrings/fc.public-2025.key
# cat /etc/apt/keyrings/fc.public-2025.key
-----BEGIN PGP PUBLIC KEY BLOCK-----

mDMEZtA0dhYJKwYBBAHaRw8BAQdA4W68l0ORR48MNbXOTH1vbFTYJiZALz5Qa342
...
OBNdp7i4CEn30rTLVLNOdjoz9b9reQEA+XDfkiuPMc2jdz+3fRNfN7blyu52jkj5
wdC+2pHIzQY=
=W17c
-----END PGP PUBLIC KEY BLOCK-----
# apt update
Hit:1 http://us.archive.ubuntu.com/ubuntu resolute InRelease
Hit:2 http://archive.trinitydesktop.net/trinity/deb/trinity-sb resolute InRelease
Get:3 http://silk.apana.org.au/debian trixie InRelease [9,453 B]
Err:3 http://silk.apana.org.au/debian trixie InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 87E7A67D10BB5BF8
Warning: http://silk.apana.org.au/debian/dists/trixie/InRelease: The key(s) in the keyring /etc/apt/keyrings/fc.public-2025.key are ignored as the file has an unsupported filetype.
Warning: OpenPGP signature verification failed: http://silk.apana.org.au/debian trixie InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 87E7A67D10BB5BF8
Error: The repository 'http://silk.apana.org.au/debian trixie InRelease' is not signed.
Notice: Updating from such a repository can't be done securely, and is therefore disabled by default.
Notice: See apt-secure(8) manpage for repository creation and user configuration details.
Notice: Missing Signed-By in the sources.list(5) entry for 'http://archive.trinitydesktop.net/trinity/deb/trinity.sb'
#
I don't remember Forky or Trixie giving any trouble like this. Does Resolute need to
be configured differently?
--
Evolution as taught in public schools is, like religion,
based on faith, not based on science.

Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata