I got this once update on Ubuntu 22.04, mentionable that I upgraded from 20.04
Reading state information... Done
All packages are up to date.
W: http://bd.archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
W: http://security.ubuntu.com/ubuntu/dists/bionic-security/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.