The mechanism used for key handling is not inline with Debian best-practices.
“The key MUST be downloaded over a secure mechanism like HTTPS to a location only writable by root, which SHOULD be /usr/share/keyrings. The key MUST NOT be placed in /etc/apt/trusted.gpg.d or loaded by apt-key add. A sources.list entry SHOULD have the signed-by option set. The signed-by entry MUST point to a file, and not a fingerprint.”